People bring up the chinese clear a lot, but those people played on other servers, developed strategies, and researched a lot to be able to do that. They also had the BEST party makeup possible for the fight and still only beat the enrage by 1 second. They definitely wouldn't have cleared with a paladin, as an example.

Best doesn't mean only, but if a class isn't included in the 'best' setup, sacrifices usually have to be made.