I already said nothing wrong with AoE killing, it's when taking all the mobs in the zone
It's literally impossible for one group to take all the mobs. They despawn after you pull past roughly 1/4th of the total distance of the donut. So you can assume there are at least 4 groups pulling for competition.
I can't speak to other servers. But on Odin most mlvl parties seem to last 1-2hrs at a time. I have yet to see it become such an issue that you cannot play in Crawler's Nest [S].
^And this standard of 'unplayable', I'm going to once again compare to Gain EXP in Escha-Zi'tah back pre-sparks nerf. Whereas, you could only reliability pull 1-2 mobs per go due to such competition. I've not seen this here yet.