This is also an interesting case for github. youtube-dl is popular enough that this just
might annoy enough people to find an alternative way to collaborate on it. Meanwhile github becomes “that platform that might kill you project”
Linux kernel is developed[0] nicely without GitHub. All that’s really needed is a mailing list and someone (who doesn’t fear Google or RIAA suing them personally) willing to host the DVCS server.
Git ships with a server daemon so no third-party hosting is strictly required. In addition, Git has tools for creating and incorporating patches that can be sent by plain email. I believe that’s how Linux development works.