I think a lot of people misunderstand what git really is for large software organizations. It's not their version control system. It's the set of primitives on top of which their version control is built.

Monorepos are one such VCS, which personally I don't like, but that's just me. Otherwise there are plenty of large organizations that manage lots of git repositories in various ways.

Replacing git is a lot like saying we should replace Unix. Like, yeah, it's got its problems, but we're kind of stuck with it.