This is one of those things where the game was working as intended and Blizzard just said... ooops, we messed up, sorry you were doing this and thought it was legit because the game was working as programmed but... BANNED.
We used to stack Dragon Soul LFR’s with classes, armor types and token sharing classes. Then... personal loot and coin rolls ended those good times.
I think we got 10 guildies 4 piece farmed inside of 3 weeks and even one or two week one. As bad as Dragon Soul was/is, it sure was easy to get people geared.