WoW Story is not really told in game tho, it’s more or less told in the books. As the “lore” we see ingame is often just like this.
You: The Hero, you try to kill big bad buy.
Big bad guy: I’m litteraly unbeatable until the last patch 
!
You: Haha last patch is here, time to die!
Big bad guy: Ohh no i’m dead now 
EPIC NEW CINEMATIC FOR NEW EXPASION HITS!
And it’s a repeat of exactly what you did before.
It has been like this since more or less Launch of WoW, all though Lore was kinda set in place from the Warcraft Games and they just more or less adopted it to WoW as Expansions.
And to top it all off, we can count ourself Lucky if the lore stays like this and doesn’t get changed 3 Expansions later, i mean “Nathrezim from the Planet Natherza” is now “Nathrezim are from Revendreth”.