I remember back when I first was deciding whether or not to host Kestrel-3's pages on Github or not. #fossil was one choice on the table, and was actually a strong contender at the time.
Reason being, #fossil is relatively easy to port compared to its competitors. To port Mercurial, you need to first port Python and enough of its supporting libs to run it. To port Git, you need to basically clone an entire Linux distro's user-space.
Fossil would have let me eat my own dogfood quicker.