Blizzard decided to stick us in t4 for months for no real reason instead of just giving us the expansion the way it was originally.
A huge amount of people play WoW exclusively for the endgame content. They don't care about doing the leveling experience a bunch of times on every different class, they don't care about doing 5 mans past their gearing relevance, they don't care about all of the random fluff that you could distract yourself with if you want to.
It doesn't mean they're playing the game "wrong" any more than anyone else is.
Back in original TBC my guild didn't enter T5 until the best guilds on the server were already clearing t6. We didn't feel betrayed by blizzard that they didn't give us long enough or something, we were casual. We went at our own pace and saw all of the content by the end of the expansion like everyone else, and it was completely fine.
So I don't really understand why theres so much pushback around here on blizzard just releasing the content quicker.