Rather than a weird "cult of personality", the fact that Git demonstrated with Linux that it could handle a relatively large amount of source code and allow dozens (hundred?) of programmer to work on it "asynchronously" were key factors for adoption, I believe. If SVN was that good, as it was already well-established online (Github was not the first online VCS frontend, far from it), it should have remained the king of the hill. But it was decapitated instead.

As someone who's worked at a company using Mercurial, the wild fire was that everyone was begging to get onto something better and less opinionated.

Mercurial was slower than a decaffeinated sloth. It lost because it sucked. Sorry.