Eh, in a myopic sense yes, but folks are using Microsoft GitHub for their CI, issue tracker, forums, kanban, Wiki & so forth. By choosing their Markdown fork, you are locked into that too. Some communities like Elm, Unison, Nix use MS GitHub as your primary community identifier (Elm doesn’t even allow you to create packages on another platform). Many tools only allow MS GitHub single sign on. If you fork off of MS GitHub, in most scenarios you’ll still be required to have an MS GitHub mirror or you won’t be able to submit a pull request as most projects don’t have an alternative contribution channel.

Some of this can be migrated, some of it can’t & the whole time being entrenched in MS GitHub land projects will fear friction & loss of users/contributors if they move (& the platform they would move to likely isn’t offerering anything more than being open source).

So can you just move the code elsewhere since Git is a DVCS? Yep. But projects are more than just the source code.