[immibis]

Sourceforge isn't GitHub. What's the relevance?

If you think SF+CVS is equivalent to GitHub+Git then you never used SF+CVS. Git won because of GitHub, specifically, not because generically it could be hosted on the Internet.

[CRConrad]

No, GitHub won because of git, lots of VC (later MS) money, and brilliant marketing that makes people think "Git won because of GitHub".