alt Hacker NewsYou can (and people did) do same kind of tooling based off git protocol and storage. Hell, even one for distributed code reviews.
It just... never was something majority actually want so they didn't really get any traction.
Issues wise you also get few nasty cases where you really do not want to keep it with project, like having clients send a bunch of screenshots or even videos of triggering some bugs can grow storage pretty quickly... and while extra few GBs on a file server isn't a big deal, keeping it with code repo just so someone can look at tickets locally is PITA, and you quickly get into "let's not use it, it just makes everything complicated and everyone repo bloated".
Someone could probably implement most of fossil features using git as backing store without all that much problems, the wiki/issues/whatever else features would just be separate, parallel branch hierarchy
Those screenshots and videos are taking up space SOMEWHERE, whether it be your inbox or your filesystem, why not have them as unversioned artifacts in your db? (Fossil supports this). Of course if you have multiple people working on it and many assets, other solutions would be better (shared cloud drives, etc). But for my use case of a storing textual information only (and perhaps a demo video, which many Git users often keep a video in their source and link it in the readme), Fossil works great to keep all my stuff together in the same context.
I explicitly dislike the idea of using Git as the backing store. Forget the fact that Git is not native on Windows and is immensely bloated; the actual .git folder is a mess for backup systems when working locally compared to a single database file.