You can still clone and grep, can't you? You can't file issues or submit PRs through Github without an account, either.
In other words, GitHub is no longer suitable to host open source repositories because of all the closed "extras" it adds on top.
They're shady AF, but some features require an account not because they're moat water but for some other reason.
It's clear the "extinguish" phase of Microsoft's open source venture has started. There're plenty of very good alternatives, it's time to move on.
http://vger.kernel.org/vger-lists.html
Unless you count your ISP of course.
probably for the best.
Are these now also no longer "open source"?
No.
None of this is somehow a core requirement of "open source".