They actually do. Ppl get hyped about how many WOTLK had and ignore the fact it PEEKED during WOTLK. WOTLK was riding the momentum of Vanilla and Burning Crusade but it is also the point duel spec made class and spec identity irrelevant. LFR made server identity and reputation irrelevant. TLDR WOTLK is where WoW really stopped being the D&D type MMO it was set out to be and when the game started to slide.
Momentum of a great game and expansion, and Arthas hype propelled the game to big heights. But the game didn’t have the quality needed to maintain and grow itself like Vanilla and BC did.