I don't understand GitHubs popularity in the first place... You have git as the interoperable version control "protocol" but then slap proprietary issue, PR, CI

I don't understand GitHubs popularity in the first place... You have git as the interoperable version control "protocol" but then slap proprietary issue, PR, CI and project management features on top that one couldn't bring with when migrating away? At that stage what is even the point of it being built on git? Also, for all that is great about git, I don't think it's the best version control system we could have at all. I wish we'd do some serious wheel reinventing here.