This is one of the weirdest things about this game. I finally bought it about a year ago and was surprised by how easy it was. I then manually switched to a higher difficulty, and then to the highest available, and it still was a lot easier than anything I have ever played. When I faced Diablo, I literally never had the chance to do anything to him; my crowd just stampeded him in several seconds. And that was on highest difficulty available. At the same time, I clearly remember watching a video from about the second day after release with a Barbarian player fighting Diablo for half an hour, almost dying several times during the fight. Something obviously went terribly wrong somewhere around like 2015.