While Blizzard did some ridiculously bad choices like scaling mobs to contribute to this feeling, the thing is that progression was missing from the game since WotLK. In BC you could grow your power compared to the world and the “noobs” during the expansion and got reseted only on new expansion day. In WotLK it was every patch with catchup mechanisms, so you couldn’t really outgrow the others or the new content.
I started to lose interest in the game and finally quit it. Or – as I use to say – I didn’t quit but play optimally: the easiest way to get gearscore X is to wait until it becomes catch-up.
Now the truth caught on these bloggers and others, my comment is merely “what took you so long”? Maybe Blizzard did better job concealing the lack of progress and you didn’t care about the reality till the feeling was there? Or nostalgia ran out?
This is why it’s important to rationally evaluate systems and leave when you see it’s broken and not when the collapse reaches you. Of course I’m not innocent of lingering, I kept playing EVE half year after Falcon made it clear that I shouldn’t. But me being guilty in the same thing doesn’t make it less wrong. WoW lacked “real” progression (compared to the existing content and the average player) long ago.