Well first there were mmorpgs that constain alot of mob killing to lvl up, then they got complained alot saying "why theres no quests plaah plaah". Then Devs and GMs liked the idea and added crazy quests to prevent "grinding". Lol just my theory. Well theres alot of mmorpgs that have both equalled but because theres also alot of quests, ppl prefer quests than normal lvling. For example Cabal online, some ppl said that if you do normal lvling from 1-30 you will get faster than doing quests, some ppl were on different line.