Comment by number6
Yes - this is exactly the problem. Big Corporations, like Microsoft, the owner of Github, can shut you out. If you lose access to your E-Mail, or anything connected with your Microsoft Account (or Google Account) you will lose access to a lot of services that relie on it. And if you keep your source code with Microsoft and Microsoft only, you can lose access to it too.
Broadly speaking this tendency towards concentration and centralization is not only just going on in all aspects of society all over the West, more baffling in many ways is the fact that many of the instances of concentrating power and control is being facilitated and even perpetrated by the collective people themselves, e.g., putting all the eggs into the GitHub basket.
Regardless of why and how it’s happening, it seems extremely risky at best because all concentration of power and control tends to beget more abusive power and control.