Speaking personally, definitely no. Even before I heard of git, I did not like SVN. In particular, it made an error I don't hear many other people mention where directories were checked out to revisions, rather than entire repositories. Consequently it was very easy to accidentally update just a subset of your repository, and have your whole repository in a state that didn't exist in the version control system at all. There were several times there were builds that were completely unreproducible because it turned out that they were, technically, r83726, except this directory was r84713, but this other directory was r78372 except for a subdirectory that was r84299, etc.

That problem I saw even before I saw a replacement.

But once I saw git, having a full copy of the repo was pretty killer. It was also better at merging, partially for having the history local. In fact I recall some SVN people protesting at the time that merging wasn't so hard, but in a nutshell, they were just wrong. It was harder. Source control that can't merge fluidly is pretty limited from the get-go. There's literally entire dimensions of things we do with git that were so impractical with SVN that only the very largest projects could afford to do them, with the whole "workflow" question. Now you don't even hear about the difficulties of merging since all the open source SCMs copied each other and "good merging" is just table stakes now.

The problem is is that git doesn't really have fatal flaws, it has annoyances, and that's not the same thing. "The UI is difficult" is an annoyance for its target audience. Most every other criticism I've seen of it is an annoyance, not a fatal flaw. Fossil doesn't solve a problem I have with git. It has some neat ideas and arguably does solve some problems, but it doesn't solve the problems I have with git; you could lift Fossil's solutions to wiki and bugtracking and just put them in Git and I'd probably be happier with that than Fossil itself.

The problem isn't that Fossil is an SCM competing with git; the problem is that Fossil is a monolith competing with the rapidly-moving git ecosystem. The former is perhaps beatable, the latter is a juggernaut. All of Fossil's other features sitting in git is something that might get somewhere, but if the base source control isn't git-based, I can't sneak it into a work project to try it out. I've got a corporate mandate that all source belongs somewhere standard, and it's a perfectly sensible requirement for someone paying me to do a job.