Having a first experience with Zotero (helping my wife in her academic writing process) with Word, I can easily see how DEVONthink does not do what Zotero and Word do together. I presume the other citation manager applications are similiar.
Yes, there are overlaps in that Zotero and DEVONthink stores documents and information about documents, but far as I know won’t help with making the writing of the paper and making citations and bibliography easier as Zotero does. And yes, probably some scripts can be developed to make it so. DEVONthink could even do something in the far future, perhaps. I notice that elsewhere on this forum people are posting things about Zotero and DEVONthink but to me is well too esoteric to go there in support of my wife who has no time for anything related to learning how to use the computer in a better way.
So yes, for you DEVONthink may not be a good fit at this time if you really want the automation that a citation manager helps with writing.
FYI, when I do a paper that will be written and published with LaTeX for final PDF, I do it all in Scrivener. In my world I don’t have to mess with strict rules about citations so I collect all the reference documents, and notes about the content in those documents, in DEVONthink Groups and Smart Groups. DEVONthink lives on 1/2 the monitor, and Scrivener is on the other 1/2. At that point I forget about the software and get on with the project.