Fossil looks neat, but it didn't look "sufficiently better" than Git for me to bother changing, especially due to all the services that support Git out of the box.
Git (not github) was built for bazaar style decentralized development where people might contribute a single patch or two, and it scales really well (see Linux). People don’t even need an account to contribute, they can just send a patch via email.
Fossil was built for cathedral style development, where you’re a small team of trusted contributors. You get offline first issue tracker, wiki, forum, chat etc. out of the box and integrated into an easy to backup solution. Allegedly it doesn’t scale as well though.
With hosted services like Github, I feel like fossil doesn’t buy much more than offline first capability and simpler to use. However if you self host, fossil is dead simple run (single binary) and to backup due to it generating a single SQLite file and it’s easy to stream changes elsewhere. Setting up git with gitolite, email list, issue tracker etc is much harder (though I’ve heard gitea is easy to use).
In terms of Fossil as a technology, it's an SCM with built-in project management tools (wiki, forums, bug tracker, etc) so it does much more than git does.
I don't really agree with this assessment of rebase. I think there is value in squashing commits on dev branches into logically distinct sets to keep the log cleaner. In the case where the reason code is doing something that is not obvious I think that explaining the reasoning or the journey to that point in a commit message is clearer than the complete history of trial and error to reach that state.
