I don't play retail and don't understand this thread. Optimization while leveling has always been a thing, even in classic.
The only difference is, now we have a bigger audience of players using the internet. Often on the internet people go to forums to "COMPLAIN" and not to provide constructive criticism, just like the OP here. Bitching for the sake of bitching I guess? Or because they are ignorant to the fact this existed in vanilla... This is a obvious trigger post to try to get people to argue.
If you really believe that this didn't occur in Vanilla... you are just plain wrong. There were always players trying to do things "Faster". Players "Power leveled" in vanilla, just they didn't stream it and because it wasn't streamed, it never got as popular.
I've had 0 issues finding either AOE groups or normal groups just looking to clear the content at a steady pace. I did 3 SM Lib runs yesterday that was just chill and no one was "AOE SPAM BLAH BLAH BLAH". I don't care how other players decide to enjoy the game. I also see 0 point in posting this crap on the forums to just start flame wars and "internet" fighting.
OP is lame and just trying to trigger people. I know they are coming off as "innocent" and just trying to ask the question, but lets get real... It is brought up so often that I really think some people in this world or just plain stupid to the point that they are pathological liars who kid themselves everyday.