I know you’re taking the “strict teacher” approach with your comment, but you’re totally wrong. And the reason you’re wrong is, security doesn’t equal privacy. But for the “average person,” security does equal privacy, or should, so they find systems that could potentially expose their identity to be “insecure.”
In this particular case, there have been past examples of using keys to fingerprint users without their consent. Yes, it’s been super edge-case and proof-of-concept, but for a lot of people — and perhaps more importantly, in a lot of jurisdictions — leaving a personal identifier sitting around like this (without ever informing the user!) is the very opposite of a best practice.
The end result is, you should only have a key on GitHub that isn’t used anywhere else. That’s what I do, and I’m sure lots of us on this comment thread do, but there’s definitely lots of My First Coding Bootcamp people who were guided through their GitHub account installations who might not have been aware that these are keys that shouldn’t be reused elsewhere.
I would have a very different view on this if GitHub had been explicit about the use of registered keys for other services. That’s a GREAT concept, but I’m not going to trust a company with that business when they’ve just backdoored themselves into it without asking for permission. And the problem for them is, in this particular situation you need the weird paranoid privacy crowd on your side for it to work.