Interesting. I'm not a professional developer and also love fossil for toy/hobby projects. I find it fascinating that this well crafted, solid piece of software is so forgotten, and that git has just rolled over everything.
Honestly you could sell me the best alternative to Git that exists and I still wouldn’t switch, or even try it. I don’t care enough about my versioning system to use something else than what everybody uses. Ubiquity beats convenience.
What I care about is the tooling around it: GitHub and its ecosystem mainly. I also want my open source projects to be on GitHub specifically, and I don’t want to ask contributors to use something other than Git.
Totally respect you wanting to not care about tools, but for the latter part, I do agree with you, which is why I like jj: it uses a git repo as its backing store, so your projects can live on GitHub and all the rest of your collaborators can use git. Nobody else needs to know or care.