Another reason is that MS may be in phase when it will ask to pay for using GitHub just for reads (rate limiter).
When you would usually create a PR, you use `git format-patch` to create a patch file and send that to whoever is going to merge it.
They create a branch and use `git am` to apply the patch to it, review the changes, and merge it to main.
It is nice that git supports multiple remotes, though. It feels good to know that `git push` might not work for my project right now, but I know `git push srht` will get the code off of my laptop.
I also had to setup a bidirectional mirror back when bandwidth to some countries was restricted. We would push and pull as normal, and a job would keep our mainline in sync.
It is sad that most organizations forget that git is distributed by nature. We often get requests to setup VPNs and all sorts of craziness, when a simple push to a bare mirror would suffice. You don't even need anything running, other than SSH.
Well, that's how it was designed to work! The whole point of Git is that it's a distributed version control system, and doesn't need to rely on a centralized source of truth.
The real reason not to use github anyway though is that it's terrible (the basic "github model" for doing code review was basically made up on the back of a napkin IMO)