I would argue GitHub does a lot more centralization than just those two. It's an entire developer platform centered around Git. It does hundreds of other things that some developers use, and some don't.
Collaboration, issue tracking, Actions (CI/CD), Codespaces, Security, AI, Identity, social, hosting. Those are like broad categories I can think of off top of my head too you could fit probably 10-15 "features" into each of those.
