Syncing ideology of DEVON

First I met DEVONthink To Go and the Database Edit-Then-Sync solution was crazy for. I am using in my mind the theory of server-based database, like in Evernote or smth., that gives me power to-not-to-think where is the Hell my Data is. I just open the app, and do whatever I need. All the rest the app did on it’s Backend.
I spent a week or more reading all this tutorials and even a book about how does all this works. But I still can’t understand one thing: why the Database is always local? What is the Role for clouds or WebDAV server is? It just keep Metadata to synchronise and keep Database updated?
According to the [url]DEVONthink Database Size] topic there can be a limit of using Database on slow devices. Or with small capacity. So I want to ask: why not store Database online or on WebDAW server instead of my own computer? I’ll provide required space on any supported Cloud Service or my own WebDAW server. Why is this, more relevant Practice for me are not available? Or I just don’t know “How to?”?

Because… (1) cloud services are NOT data-safe for DEVONthink databases, and (2) because cloud services are beyond your control and the remote access isn’t inherently stable. Where’s your database when Dropbox’s servers aren’t responding?
What if your login isn’t working and you need to contact the cloud service’s support team to try and login… just to get at your database?
What if your network goes down while you’re in the middle of working?

Local resources are ALWAYS faster and more reliable than any remotely accessed resources. It also doesn’t have dependencies that are outside your control.

I’ll speak from personal experience here - I find too many situations where my internet connection is insecure, slow or unreliable; I don’t want to be hostage to a poor connection when I need some information.

I’ll second that. Too often I am without reliable or fast internet. Sometimes weeks at a time.