GitHub is down
status.github.com
status.github.com
It's come a very long way in the last 12 months including unlimited private repos.
The problem is, on a daily basis when you're looking for an open-source project, where do you find it? It's always on GitHub. It has established itself as the market leader.
It happens all the time. Other companies may provide better support for certain things(private repos in this instance) - but people flock to where the rest of the market is. It's like PayPal, we all know they're better alternatives and yet we all still use PayPal.