Sure, that's a fair point as well (though bzr came out of GNU arch, which didn't originate at Canonical, and it was finally redesigned into something good at Canonical — not a knock on arch either, it was simply early).

The question then becomes: why not Mercurial which still had a better UX than git itself?

My point is that git won because of GitHub, despite lots of suckiness that remains to this day (it obviously has good things as well).