What about git-annex for the large asset files?
Does it have to be a goal for Git? Most of the development is not game development
But there's no good fundamental reason why it has to be that way.
The general point is: Git mostly works fine for what it is, but version control can 1) be easier to use, and 2) serve more purposes than Git currently does.
Imagine a perfect, seamless version control system that does everything you want with minimal effort. Git isn't that, not even if you've put in the time necessary to become an expert.
Note I love git, but I don't know any big game studios using it. Some indies get by because their games are smaller but even then it can be a pain.