any class from birth can buy a pet from the elven kingdom to aid with leveling, on top of that most non melee and rogue types can summon a golem as well using a scroll. those two pets alone should get you to 25 at which point you can get a professional soldier and the golem will still help a bit. Yes i know the scrolls cannot be killed for at low lvls but you can buy them from someone im sure its a lvl 15 golem, nothing too OP here.
i think most of the leveling issues come in the 38-50 range where mobs become too hard to solo with alot of classes and parties are few and far between, because alot of people have stopped at 30 for apps and/or training.
I'm not apposed to the idea but perhaps after lvl 30 start increasing xp from quests.
I personally love the interaction, i will find things to do until i find a group even if i can level alone for the opportunity to meet new characters and build new friends / enemies.