I actually wasn't clear at all. To me, it's more about code browseability, and I've found it much easier to splunk through codebases for fun in a GitHub-like interface. (Not much to do with the developers' workflows, I suppose)
That's really where it's coming from, wasn't really trying to be snarky or anything.
If you can say "easily" for this, you can't have tried actually importing the OpenBSD CVS repository into git. cvs2gitdump doesn't do too bad of a job, but doesn't attempt tags and branches. I haven't found another conversion tool that gets anywhere close.
I'm not suggesting that CVS to Git is easy. I'm just saying that Github doesn't present any kind of barrier to adoption of Git (in any project, not just OpenBSD).
No, Facebook and Reddit, big as they are, don't make their own browsers and are still individually minorities in the grand scheme of the world wide web.
Git is used by a comparatively small captive audience; most git users are invested in GitHub. MS is well positioned to run their "embrace, extend, extinguish" play if they wanted to.
That's really where it's coming from, wasn't really trying to be snarky or anything.