None of your examples make any sense at all.
Class stacking on HM Nef was a failure of Blizzard's mechanics, not any sort of exploiting or cheating. They did the boss exactly as he was supposed to be done just with more Druids than most people would think to use.
Saronite bombs on Lich Kings weren't recognized as a world first. The achievement was stripped from them and they were suspended.
World First guilds don't queue for LFR.