Ever work on a AAA game?
Obviously a 20 year git repo with all commits is going to be massive, but you don't need that locally.
Also, it seems like it would be reasonable for a AAA game to version control assets separately from code.
Even with a git history, wouldn't that only be maybe a few hundred MB?
People usually mention git-lfs at this point, but that is always annoying to use in practice. There is also shallow-clones and sparse-checkouts, but these only mitigate the problem as there is no way around cloning at least one revision completely with git.