but they do, because all the devs know git and are only using mercurial because they want to send you a pull request, and now their feature branch is forever.
Mecurial is unforgiving of mistakes - once in the repo, they are forever.
As for MQ, I've really tried to understand it, but it's just profoundly awkward IMHO. Mercurial's main benefit is that it's much easier to use and understand than git, so if I'm going to need to fire up the extra brainpower, I might as well learn git where these advanced patterns are extremely commonplace, and are part of the core functionality, not as a series of optional extensions that have been bolted on over the years. I've almost never seen anyone using MQ or rebase with mercurial (or even bookmarks for that matter).
I've tried carefully in my post to express that my points are all based on an overlap of social with technical issues. I am aware that technically, hg has answers for all these things. But these answers don't pan out in the real social world, for better or for worse. If git didn't exist, I'm sure there would be a much larger knowledge share for mercurial, and I was even betting on that in the beginning (certainly the "easier" tool will be more popular?) but it hasn't turned out that way.