As someone who uses Git for technical writing and Word's revision system for fiction that goes back and forth with an editor, I mean, sure, it's sort of a merge request, but you need to place a higher value on the "goes back and forth with an editor" part of the requirement than I think you are. :) An editor suggests changes, sometimes by editing directly and sometimes by leaving comments, that the author can accept, delete, or modify, right? If we're talking about technical writing that's already in a Git repo, then using a PR review system like GitHub's is an acceptable substitute. If we're talking about somebody sending a story to the New Yorker, we're not.

What, and do seperate commits and merges for every comma and dangling modifier? That makes no sense. In addition, there needs to be comments and queries.