GitHub solved the original "code collaboration" problem, and now it's a default easy way to outsource repo management. It also has the most integrations. A lot of companies grew up using GitHub.

GitHub was, once upon a time, quite stable. Things have changed: more features, more usage, and automated agents.

I know what it does, but why is it such a problem that Actions is down? I think you did kind of answer it: "A lot of companies grew up using GitHub," i.e., they are using it as infrastructure by default, not because it does something that otherwise can't be done.