Players from WoW have been suspended for exploiting raid content, among others, in original vanilla Naxx if you killed Heigan during the dance phase on the platform, you could loot him and he would respawn.
On the flip side for Kripp, he knew this wasn't "working as intended" and should've known better than participating. I personally do not agree with a permaban, but ideally if you have an influence, experience of other MMOs (and their policies) he probably should've told the people who was telling him about it to stop it and tried to get in contact with someone about this problem.
It really sucks for those that are coming into this game fresh, don't know the back history of MMO polices, don't go on reddit, forums or whatever and come across this situation in game. Seems simple enough, buy something for cheap, vendor it for a profit. Why not continue to do it?