Is there a way to do the equivalent of Word's 'track changes' feature in Vim/Neovim? As an editor who reviews manuscripts in Word, I want to be able to make edits, have the author review/approve them, then clean up the result into a file that goes to the typesetter. If I could do that, then a plugin like this becomes potentially more useful to our workflow.

Other commenters have mentioned entering one sentence per line as a good way to track revisions in git.

You could then use a git workflow to do your reviews and edits.

A source control tool such as git or mercurial will solve this. Any collaborator who uses vi should have no issues with a git/hg workflow for managing changes.