Word's review functions appear as pretty colored bubbles and a bunch of icons on the Ribbon. It's easy enough even for Humanities professors to use on a daily basis, despite the fact that as a VCS, it's strictly inferior to something like git. Actually, I think it's popular precisely because it ain't git. Most professors who are fluent in Word's review functions would be hopelessly lost when faced with a Dropbox conflict, let alone merging git repos.
Totally agree that word's review functions are really simple. Which is why even all legal/contract documents are exchanged back and forth between companies in Word today. The hassle is that its done over email - sending versions of attachments back and forth. Nice naming convention helps, but there are definitely better solutions to do the same online today.
Actually, most big law firms do not use the built in track changes function in Word, they use more specialized (and in my experience, better performing) software that take a "before" and "after" Word file and then generate a nice "redlined" version showing insertions, deletions, moves, etc. in different colors. Examples include Workshare DeltaView and Litera Change Pro.
I think you're absurdly underestimating people. A diff is a bunch of lines removed, and lines added. That's a pretty damn natural representation.
As for git's complexity, it's all in its completely opaque display of its internal state. A chain of deltas - diffs - isn't complicated. It's all git's (perverse) desire to follow the exact-same command-line interface as cat and awk, when neither contain persistent state.
It's not the concept of a diff that baffles ordinary people. It's (a) the lack of an intuitive interface, and (b) poor integration with natural languages, that make most VCS's difficult to use in the context of a word processor.
Word shows pretty bubbles next to sections that have been edited. The bubbles are color-coded so it's easy to tell who did what. The edits can be accepted, rejected, or further modified with a couple of clicks. There is no list of commands or keyboard shortcuts to memorize. Just a bunch of icons, menus, and clicking around.
Word doesn't require your content to be made up of neat lines of verse, either. Natural languages don't organize themselves into 78-char lines. It should be OK to edit a few words in a long paragraph of prose. Even Wikipedia's messy "Revision History" is probably better than git in this regard.
'a bunch of lines removed/added' is a great representation for stuff that consist of semi-atomic lines, like code.
It is a horrible representation for stuff where edits may consist of both typo fixes, and separate wording changes in a single sentence - where you might want to accept change to one word and reject change to another word, despite that they came from a single "commit" to a single line.
For collaborative text editing both word's track changes and google docs features are far superior to git.
FWIW, I don't often encounter diff output in my day-to-day computer usage, but when I do, I do not find them very intuitive to understand. A bit of UI magic would help here, it's not the concept that is hard (for me) to grasp, just all those lines with +'s and -'s and figuring out the contexts in which they apply. It's always a bit of a puzzle, especially if, for some reason, it's not highlighted with colours.
Word's review functions appear as pretty colored bubbles and a bunch of icons on the Ribbon. It's easy enough even for Humanities professors to use on a daily basis, despite the fact that as a VCS, it's strictly inferior to something like git. Actually, I think it's popular precisely because it ain't git. Most professors who are fluent in Word's review functions would be hopelessly lost when faced with a Dropbox conflict, let alone merging git repos.