Well it all comes down to what metrics you use to decide the importance of social networks, doesn't it.<p>If you're judging by the ability to interact with your real life contacts online then facebook is probably the best social network(gah!)<p>If you think that meeting like minded people & having awesome interactions with them is more important, then maybe Google+ is the most important social network.<p>If you agree with Jane McGonigal that games can help make the world a better place, then WoW is probably the most important social network.<p>But if you think that collaboration on software is more important(and facebook & WoW are softwares), then GitHub is probably the most important social network.
It all depends on what you rate higher.<p>And putting myself in the shoes of the writer, I think it's the end product that comes out of social networks, is the metric he's pointing to. While other social networks directly affect the lives of more people, much much more than GitHub can ever hope to, the products coming out of GitHub are, or would soon affect more people than any single social network could hope to do.<p>Someone out there is building the next facebook, the next WoW, the next Linux, or maybe the next Google and it's likely that GitHub will play a part in it.<p>Keeping that in mind, I'd say that yes, GitHub is maybe the most important social network on the internet.