They aren't using opinions. It's fact. It has nothing to do with video cards. Your game would perform just as well with a single card of half the power you have in either of those. Your good performance has to do with t he fact you have some of the best CPU's on the market, clocked at a very respectable speed. You do not gain almost any performance from dual or triple cards in WoW (or rather , particularly in raids)
Though, you are correct. WoW is not 'improperly optimized', it simply doesn't benefit from more GPUs, because the bottleneck is not a GPU situation.