> I mean... git repositories can be cloned. People that depend on libraries can vendor them, or outsource that job to someone else (like Google's go module cache / checksum database). Using git does not make your project vulnerable to the whims of Github, and it doesn't make your users vulnerable to the whims of Github.

The thing is that Fossil is not just the code source, it's the issues, wiki and all the information around. Basically a self-hosted GitHub, so you can take all information with you, not just the code.