Koreans are mechanically better. Not because of some innate voodoo, but because they don’t do things in halves when it comes to LoL. Come and play here and you’ll soon realise that everyone - from Iron to Challenger - is limit-testing. I’d say most (~60%) games start with just a level-one 5v5 brawl in the river. And the following lane-phase is bloody as hell. Don’t expect low elo junglers not to invade you. They will be in your grill. Then, as you climb, the aggression goes up, as does the CS. Consistent with other regions, at low ranks, CS is atrocious. Anyway, as a result, the cream of the crop have god-tier mechanics. And then give them a bit of coaching and whatnot, boom, new pros.

EDIT: Oh, and infrastructure. Korea has very toxic sports culture, but e-sports is different because pro gamers don’t have alumni and all that crap. If you watch team vods, you’ll find coaches and players are very respectful towards one another.