Really level 21 i did the math the XP you earned back in 7.3.2 would of made you hit 24, its hardly the biggest difference.
Also people seem to be forgetting because zones and quests scale you don't out level the reward, handing in a quest thats 2-3 levels below your level netted you very little xp now the reward scales with you. I'll admit it take a bit longer to level due to not being able to spam Shadow Word Pain on 10 mobs and have them all die from the one Dot but how was that considered acceptable game-play.