I'd like to know if most people use GitHub because of the social network part, or other reasons. I, for one, hate the social network part.

One thing with GitHub for open source projects is that the CI is free (and included macOS runners). The other is that many people have a GitHub account and would refuse to contribute to a project on another forge if it means that they must create a new account.

The federated design of Tangled solves the latter problem, so there's that.