You would be surprised how many people develop directly from github, either by using github’s web editor or a third party editor. Even if one does not do this,

You would be surprised how many people develop directly from github, either by using github’s web editor or a third party editor. Even if one does not do this, poor backup hygiene is the norm not the exception - for most devs I would would be willing to bet a sizable sum that github is their most reliable and longest lasting repository of code they have.