On the contrary, it keeps Scrivener projects close beside ancillary research files that you may prefer to be in DEVONthink. Plus, they can be synced in the variety of ways that DEVONthink allows you to sync - and manually, if you like, too (meaning when you want to sync them), which you can’t do with Dropbox or iCloud on its own.
I use Scrivener “package” projects in DEVONthink without problem.
Having said all that, one does have to jump through a few template hoops to get decent RTF files to write in, and the columnar widescreen list-view (the best it can manage on my big iMac), is severely lacking visually, in comparison to say, Keep It.
(Don’t get me on DTTG, though - editing RTFs on that on iOS is a no-no, again, quite unlike Keep It.)
DEVONthink is mainly useful for its centralised databases and its syncing mechanisms. Apart from text files (at a pinch), you open things in their default apps, just like in the Finder. You’re not supposed to think of DEVONthink as a Finder-enhancement, but that’s precisely what it is.