It's Oqueue. It's not about skill. It's about ilvl and trying to get gear as fast as possible with as little effort as possible. Doesn't matter if the 550 toon does more dps than the 565 toon. The raid leader will never know b/c they want to get the run done as quickly as possible and that means just grabbing high iLvl and not taking the chance with someone with lower gear.