I do not think that's how it worked out for GitHub: I'd rather say that Git (as complex as it was to use) succeeded due to becoming the basis of GitHub (with simple, clean interface).
At the time, there were multiple code hosting platforms like Sourceforge, FSF Savannah, Canonical's Launchpad.net, and most development was still done in SVN, with Git, Bazaar, Mercurial the upstart "distributed" VCSes with similar penetration.
At the time, there were multiple code hosting platforms like Sourceforge, FSF Savannah, Canonical's Launchpad.net, and most development was still done in SVN, with Git, Bazaar, Mercurial the upstart "distributed" VCSes with similar penetration.