[leotaku]

I would guess that network effects and the amount of quality tools built on top of Git are the main reason for its prevalence.

Fossil and Darcs sure look nice, but having to self-host my repositories or use a smaller company that could go under at any minute? Having to use barely-maintained plugins for my editor, CI, CD, etc.? And most importantly, having to explain a completely new set of tools to anyone who wants to work on my projects? In my opinion, it just isn't worth it.