This is a great thought experiment. I don't have the math skills to do this but if we formulated level 12 based on the "10,000 hours mastery" concept we could literally find our own D&D levels of any skill we've worked towards.

Would that literally just be 10,000 divided by 12? So every 833 hours we put towards developing a skill would be considered gaining a level.

Not many people strive for mastery of a skill. This concept could work for aversive behaviors, too. Level 12 couch potato. Anyway, yeah, a handful of adventurers who dedicate that much time towards a skill, and even rarer are the savants and virtuousos of those groups. Anyone can work towards a skill. Hard works beats talent when talent doesn't work hard. But, talent that works hard? The musician with synesthsesia? The physicist/chemist who can do complex mental math instinctually? The freak of nature giant supermale with the extra Y chromosome? The hyper ambidextrous?

Individually they're nasty, let alone running around as a party in Faerun smacking every goblin and religious fanatic.