> Its ergonomics were superior to Git's

That's a matter of taste. I used both for serious work, at the time, and found Git much more usable. My experience with Mercurial was "welcome to Mercurial, how can we help you merge and push your work in progress even though that's not what you want?" My experience with Git was one where I felt in control at all times, had a clear workflow for when I did and didn't want to publish my changes (and for when I wanted to edit them first), and allowed me to quickly make and switch branches within a single working copy.