It's not specifically github, but I believe this wrong mental model was greatly popularized by it. Until GitHub rose to fame a project had reasonable chances to

It's not specifically github, but I believe this wrong mental model was greatly popularized by it. Until GitHub rose to fame a project had reasonable chances to pick mercurial, or sometimes SVN; today the default is git on GitHub. That is the issue: when you choose a tool not because it's the best at what you want to do, but for other (very good) reasons: it's popular so you'll find help easily, more people will interact with you, etc... So, no, GitHub didn't create this, but it made it default