@KronosIII:

Sorry, the example doesn't hold up. Ensidia aren't kids. Ensidia aren't even metaphorical kids in the realm of WoW. They are literally professional players.

Besides, if they were just using bombs as usual, it wouldn't be an issue. The only way they could have been exploiting is if they were deliberately throwing them at the edges of the platform to rebuild it. That's what gives the lie to their claim that they were "just doing the encounter normally."

As far as it being Blizzard's fault for "not doing their job" I'd argue against that, too. Everyone here is assuming that Blizzard didn't know about this bug. I'd be very surprised if that was the case. My guess is they knew it existed, (as others have said, Saronite bombs are not exactly an obscure feature...) but that they couldn't do anything about it. Obviously, they're not just going to put it in the patch notes: "Known issue: using Saronite bombs makes the Lich King encounter much easier. Please don't do that." They also apparently only have a very drastic fix: removing siege damage, as they now have. It makes sense they wouldn't do that without it being absolutely necessary. It's also clear they didn't want to delay the patch until a better fix could be found. My guess is Blizzard decided to let the bug go live, and were hoping that any guilds capable of getting that far would be smart enough to know that there would be consequences for exploiting it. (Which, based on their past actions, shouldn't have been too much of a leap.)

Ensidia just thought they could get away with it; they were flouting the rules, (as others have suggested they have done before) and basically daring Blizzard to do something about it. Unfortunately for them, Blizzard didn't flinch this time.