WoW didn't kill MMO's it killed the competition because it was leagues ahead of everything that came before it or after it in every single way. Vanilla to WotLK pushed boundaries and blizzard made the very sound decision to hire elite players from end game guilds that proved they understood the mechanics better than the rest of the community and even most developers. You can put a nail in Blizzards acquisition by Activision in 2008 and as well as more Jay Wilson from D3 after the trainwreck he created to WoW development and you will notice that everything began to go downhill from there. WoW died because of the appeal to accessibility and homogenization and if you look at a graph of the player base you will notice that these trends align with the previous two events.
As far as Skyrim is concerned not only did it ride on the coattails of the jump in tech and player base but it is also saved by it's modding community. It did fix many issues the community had with the older games while remaining adherent to it's source and lore but it is also an ARPG and not an RPG. WoW was focused on RPG mechanics and a better comparison would be with TES Online which died when it started to screw with the lore and source material as well as suboptimal mechanics due to accessibility and optimization.
I am here to discuss a video game. Please do not try to rope me into anything other than that. Thank you.
