I think that’s true, but I think the only reason it moved on was the industry went 100% stagnant. In 2004, WoW was the king. In 2020, WoW is still the king. The only MMOs that came out since 2004 have all tried to be WoW-Clones with only a few minor window-dressing changes. Either that or niche games in the model of UO, that have things like full-loot, that are just not going to appeal to a wider audience ever.
The second someone comes along with an MMO that is truly the next Gen of the MMO model, you’ll see a huge resurgence of the Genre.