So your 1. is no longer markdown everyone knows, but an ad hoc, badly documented new language understandable by a tiny subset of editors/people. How is that better?
2: it is fundamentally a command line app that converts a .tex file to a pdf (and some other output formats). You can just git over that if you prefer it. The web editor is a separate application, which is very streamlined and a good option for students working together, but sure, feel free to use something else.
Yeah, collaborating in real time on the same document is pretty neat (from using google docs for this.) Having someone else typing on the same page got an unexpectedly visceral "argh! it's moving! get it off of me" reaction the first couple of times I tried it, had to switch tabs and come back later.
It's definitely only a problem for some people, and might even be specific to some aspect of the google docs implementation, I don't know yet. But yeah, that feature is not the slam dunk it sounds like, and you might not realize it until you're in the middle of it.
2. I see that I wasn't completely clear. I meant: why do we want to see our collaborators' changes in real time? To me, that would be very disturbing.