Though I found the git vs. mercurial question useful, a question's popularity does not in general indicate it belongs on SO. Look at the front page of Reddit to see what popularity can do. I'm glad SO doesn't move in that direction.

SO has a narrow purpose. There are many good questions that don't belong there. The git vs. mercurial question (and most similar questions) would be a better fit for programmers.se (and it is almost exactly the need quora is looking to fill).