Sure, I know a lot of projects have been on GH since before MS bought it, but they’ve owned it for quite a while now, so we really should be seeing better migration out by now, no?
Codeberg is nonprofit which seems more in the spirit of the Linux ecosystem overall. GH is for-profit…
Two main reasons: history and network effects.
GitHub was an independent company for a decade that provided a vastly superior service to what it replaced, primarily SourceForge. And it was free for FOSS projects, while charging for closed ones.
The improvements paid for by the closed source customers trickled out to everyone. So, it became the best place for FOSS developers, large and small. And as more people moved to GH, the more reason there was to move to it.
Of course, it was constantly bleeding money and eventually had to do something. That ended up being selling to MS.
There was a lot of trepidation about this, but for the first few years they not only kept their promise about supporting FOSS, but actually made it better by allowing small private repos to get many of the services that were previously gated for open FOSS or paid repos.
And the alternatives were stil not as good, and just as importantly didn’t have the user networking that GH does.
Now, some FOSS people are starting to look elsewhere, Codeberg, self-hosted Forgejo, and others. They have come a long way and are nearing feature parity, particularly for smallish projects. But the network effects of discovery and reputation are strong, and GH still provides a few more useful features.
I’ve moved my private repos to self hosted Forgejo, but my public ones are still on GH as push mirrors. I’m not ready to give up the discoverability and Mac/Windows CI runners that I can get from GH for free. I hope to be able to some day, but not yet.