This gives me an idea...
What if there existed an MMO where 'levels' meant abilities, and exclusively abilities? You don't have a difference in stats aside from support abilities learned and gear equipped, but there is no such thing as a 'class level' or something but there's say, 'AP costs' to learn abilities all around and AP is what you earn from fighting monsters.
It's not about wether you're level 20 or 75, but more about which abilities you've learned.

Okay, that was just a thought exercise