[velcrovan]

That is also not what is meant by decentralization in the blockchain sense. A decentralized use of git would be a graph with no central hub: each developer syncing their repo with one or more other developers directly, not with a central "source-of-truth" repo. In reality if Github disappeared everyone would just find a new host to centralize on. Furthermore Github creates lock-in by hosting data that actually would not survive any migration attempts: issue tracking and pull request discussions.