DNS is the cause of all problems, but it's also the solution - just like anyone can run Apache or Nginx, so should anyone be able to run a git setup. Then it scales really well, as everyone is doing their own thing on their own domains.
Of course, you lose out on some things like ease of user access and various protections.
You don't need this. git and a local drive. git and a shared drive. git and an https engine (can be a plugin to apache/nginx, not a full github like solution). git and ssh but people use username/password.
Of course, you lose out on some things like ease of user access and various protections.