This was already addressed by Blizzard here. Keep in mind they are using the 1.12 client which, if I remember correctly, by that time is when mobs overall were nerfed for damage and allowed for an easier time for soloing in the quest world. I don’t recall if dungeon mobs were included in that tuning pass.
Blizzard is using their own reference client from an official server at the time to internally test their stuff. I’m willing to place faith in that more than human memory which is faulty, or pserver ideas of what is supposed to be correct that is oftentimes not.