I always wonder if people prefer to use a centralised model that github seems to promote, or if people are not tooled up to take advantage of the distributed nature of git?

How technically hard is it to have an internal roundrobin git system that's synced up with the github repos needed, and then redirect to the internal git servers as needed when github goes down? I'm just wondering, no snark.

Github will go down by the nature of it being a web service. Web services aren't 100% by nature.