Trust but verify is absolutely the way that games using client side movement prediction work, and games without client side movement prediction feel terrible to

Trust but verify is absolutely the way that games using client side movement prediction work, and games without client side movement prediction feel terrible to play. World of Warcraft has problems because they don't do much of the verify part. The kind of problems you are seeing in this Diablo 3 video are avoidable, and solving those kinds of problems are essential to making a networked game.