It's very, very difficult to do what GitHub did. They combined a great sense of UX design with an extremely powerful and necessary backend product, and they figured out a way to make money doing it. GitHub's large bank account and horde of developers allows it to quickly take charge of high-stakes situations and come out on top. (This, of course, is not implying that simply throwing money at the problem will solve it...look at Atlassian Stash, a great product but pales in comparison to GitHub) Open-source projects need money and time too, but most of us don't get paid to work on open-source software, so GitLab suffers from the fact that it's no one's job to create it.

Now that GitLab is getting some funding, it will at least level the playing field somewhat.