TIme Machine can let you down when you least expect it. Your Time Machine backups can be corrupted and you haven no way of knowing until the restore fails. It is a rare Epic Fail from Apple.
Carbon Copy Cloner or Chronosync are well worth the cost as alternatives.
Any app can fail at any time - ahh, the vagaries of computing and machinery 
Time Machine is still an effective tool though I will also throw my hat into the ring re: Carbon Copy Cloner. I finally bought a license six months or so ago, and while it requires a tiny bit of reading to set up for a backup, it has performed flawlessly. That includes picking up on a missed backup if the drive was unavailable at the scheduled backup time.
Ad-hoc restoration through the app isnāt as intuitive as I thought it would be but once youāve done it one time, itās any easy enough process.
The difference at least in the failures I have seen is that when CCC fails, typically there is a specific file it cannot restore. However with Time Machine, it can fail and reject the entire backup.
Havenāt seen a CCC failure yet, but good to know
Iāve not seen that problem since I stopped using Time Capsules a long while back. They were - um - not very reliable in my experience. Today my backup disks are connected directly to the Mac. But as you know, I donāt go for single points of failure, so I use several backup mechanisms.
If I have something to share, I put it into a cloud service (e. g. a file service) and DT is indexing it - so Iāve both, cloud based sharing and DT.
Sure, thatās a pretty simple use case - a real cloud based application is much more, e. g. providing an API to connect 3rd party Apps / Services.
My 10 year old Time Capsule is still running; alternated with an external drive
Ideally, this should be a proper NAS with RAID
Another vulnerability is being local.
Ideally, a backup should be stored in the cloud (edit: one of the backups)
so I use several backup mechanisms
likewise
Ideally one of your backups should be stored in the cloud (I assume that is what you meant; the alternative interpretation of what you wrote is āthe best place for a backup to be is in the cloudā).
Mine ran - the backups to the just constantly failed and needed to be deleted and replaced. Which part of the mix - TC, WLAN, TM - was responsible I donāt knowā¦
I for one much appreciate the privacy-first approach of DevonThink. I pay for DTTG. I know Iāll never have to fear a data-breach. I know Iāll never have to worry about a service being down.
There are lots of cloud-based solutions that exist, and I happily use Bear or just plain Apple Notes as well right now, but DT3 offers something nothing else does, and I do hope they continue to do so.
People anticipating a glorious cloud-based future have clearly never tried to accomplish real work with a flaky internet connection. Our (fiber) connection succumbed to a cable cut a few months ago; I was very happy I wasnāt trying to access my 4 GB database via my phoneās data plan.
Agreed and I imagine that was a dreadful chore!
We have often mentioned The Myth of Network Persistence. I am in a relatively metro area but I can drive less than 10 minutes and be in a place without good connectivity.
Just a followup on mitigating the risk of a Time Machine failure
I recently installed Arq Premium backups for offsite (cloud) storage
Arq also supports local storage; giving me local redundancy for Time Machine
I also use two external drives (to be replaced by a proper NAS RAID)
Backing up with Time machine, CCC etc. shouldnāt be a reason for a cloud solution, but wouldnāt it be more interesting to think about multi user needs? Iām working mostly with Devonthink instead of Evernote, since a long time, as it is document oriented, allowing deeper folder structures and a way better search. But not wanting to maintain a server machine and the price tag of Devonthink Server is forcing me to keep some areas of my documents in Evernote, just for sharing doc areas with some people.
As we see from comments here Devontech business model like it is seems running fine, so I fear nothing will change, although there would be countless potential users, which are not happy with solutions like Evernote.
It seems to me that you get what you pay for. That is, the additional cost and complexity of Devonthink Server is justified by the more robust solution it offers.
Itās your data and your money, of course, but āI want functionality that Iām not willing to pay forā is not exactly a strong business case for your proposal.
For sharing documents, I use GDrive or Dropbox; thereās integration with Devonthink
This also depends on what kind of sharing is needed. You can share a file from DEVONthink or DEVONthink To Go via chat, email, AirDrop, etc.
Dropbox, etc. are not always required. 
Thanks for the thoughts of Arq. I know about it.
To be honest, I donāt even want to think about the backup.
Just like I donāt want to worry about version control (i.e. Google Docs just saves versions and I donāt have to think twice to save it in Git or some version system).
Nor do I want to worry about the version of the app that opens the data file.
I donāt want to worry about the disk space on my computer.
I donāt want to buy hardware that has to be recycled and landfilled.
Basically I want to own nothing and be happy. Thatās the plan, right?
Joking aside, the information is mine, but the storage has just been a nightmare, hasnāt it?
I mean we have gone from punch cards to cassette tapes to diskettes of various types to hard drives to usb drives to CD drives to SSD drives to cloud storage.
Backing up the entire computer isnāt very interesting and software versions change.
I much prefer how Google has done things. The google docs and sheets I created 15 years ago are still working and the space they are using isnāt a problem.
I recently made a backup of my 2TB Google Drive and stored it on a 50TB Degoo drive.
To do so, I needed to use their takeout.google.com service and download 50GB files. 34 of them in total. Then I had to encrypt them because nothing Google has is encrypted because they didnāt design their system like NotesNook has done and I donāt trust Degoo any more than Google, so I encrypted each 2TB file and pushed each of them to Degoo.
Itās not really fun dealing with media nor needing to download from one cloud to a local machine.
https://notesnook.com/#features has built the encryption into the tool.
Another company that has done this is Descript.com.
They let you download a client and the videos you process are backed up, encrypted to the cloud. If you want to store them locally also, you can do so, but you can also leave them on the cloud and if your computer blows up, you just login on a new computer and download what you were working on again. Simple and painless and the backup is to the second of your last keystroke on your transcript.
I was thinking perhaps DT can go this direction by providing the cloud storage as a paid service on top of GCP or AWS or Azure or whateverā¦ And as I add to my database, the DT client just encrypts everything and sends it to the cloud service as a backup.
Yes, I can go get Arq or CCC and I can set up a copy system and do the juggling act of moving everything around but all I want is a knowledge management system that I donāt have to think about even if it outlives me by 500 years. I want that data to just keep getting passed down the family tree with a simple subscription service that manages things like Google Drive, but with the security of NotesNook where everything is encrypted.
Does that help? Am I being unintelligent by asking for a subscription to storage/encryption?
Not sure. I figure as a human race, we need to save this data anyhow and if itās more efficient to do it on a large scale rather than each person buying disks or whatever new technology we develop, wouldnāt it make sense to just look at things from the perspective that we will always need a backup system, so build it into the products so they will last longer than our current PC hardware will ever manage?
No (thatās the only bit of you post I can answer outright 
).
What you describe wouldnāt be for me - there are things I cannot by law put in the cloud (not quite true, but the preconditions are such that, for an individual, they cannot be fulfilled). A single backup of my data would be woefully insufficient. Per se, sync is not backup - it lacks the versioning which backup offers. So if my last keystroke before my computer explodes is the delete key, and the one before was unfortunately select all, then an empty document is what will be in my sync store. As regards NotesNook, this suggests to me that for that app too, syncs rather than backing up.
Iām also going to assume that DEVONtech wonāt be around in 500 years. Although I will happily admit that my WORM media and SSDs probably wonāt work then either. So I donāt think either of us a have solution for time.
Anyway, I donāt think we will see DEVONtech implement a cloud service any time soon. As I suggested further up I assume the resources required to implement such a system would be too much for the team as it stands; whether or not expanding the team to implement a cloud service would be financially viable is - of course - something I have no data on. But Iāll wager a bet: if it were non-disruptive and financially viable with a manageable risk, Iād guess it would already have happened.
Iām not quite sure that holds water; one could maybe argue that the more the software interacts with external factors outside the control of the software developer, the more its demise could be hastened? And to be totally silly, if a relevant number of people play music whilst working with DT, should DT include the ability to stream music?
I actually donāt think your idea is silly - I think there is a whole range of people wanting different things from the software. If the software could do everything perfectly, thatād be great. But assuming the development of features is a rate-limiting factor, experience suggests to me that it might be better to concentrate on core competencies.
Music analogy is bogusā¦ if customers of software are seeing fails because of, supposedly, factors external and out of software developer control, then perhaps the software developer should address the problem and solve it internally. DT is a decade behind in simple hands off backup option and also sync options. I would certainly pay extra/premium if they had built in sync option that did not require fiddling with various options and blaming the external party [dropbox, iCloud, etc etcā¦] when sync did not work smoothly and seamlessly. To paraphrase Apple from long ago , it should just work. stop blaming other parties and come up with a solution. Yes indeed development of features is rate-limiting , but core competencies of DT are pretty darn good, sync is not. Many other softwares have superb sync and/or back ups built in. I am not a software developer, but am an extensive software user for 50 years. No one knows the guts of DT better than the developers of DT. Why they either donāt modify it so it works more smoothly with dropbox, iCloud, etc or add their own sync option, I certainly donāt know. And this is just talking about Mac sync.
Ermā¦ if the failure is because of external factors outside the software developerās control, how does the software developer solve it internally?
(Just sayingā¦) 