Remember when Xavier Dolan was being propped up as the next big thing?

He was heralded as the next Wong Kar-Wai, Almodóvar, Fassbinder. He won the Cannes Jury Prize for Mommy, and it seemed like his career was about to take off. Why did he flame out so hard? Is it because he was annoying? Is it because his US debut flopped? He made a miniseries a few years ago and it got no press.