Mercurial had a prominent role in the creation myth. It didn't influence git, but it was there at the same time, for the same reason, and at one time, with an equal amount of influence. Bitbucket was once seen as fairly comparable to Github. People would choose git or hg for their projects with equal regularity. The users were familiar with both choices.

Linus never cared about hg, but lots of people that cared about git at one point would also be at least familiar with some notions from hg.