Earlier quoted context omitted.
I'd say it's all a question of bandwidth. Geniuses just have enough capacity to converge quickly. "Incapable" people are below the threshold, so everything ends up as a cache miss, lock contention, pipeline flush; progress is so slow that they're directed onto other things. Wise people can attempt to craft their learning to converge smoothly too, they have patience to focus energy and wait for data to emerge, because…
I think this is really the key here. There is surely a natural, in-born talent for writing code, as there must be for every activity a human can engage in. But I think it's possible for people arrive at the set of circumstances that takes them from okay programmer to "talented" programmer. Time and focus I think are key, as you mentioned. People that don't dedicate enough time or focus to this craft will never achiev…
So far music school way of teaching is by sitting you on exercises while someone verify the output. That is not teaching per se, it's a black box system that has seen somehow regular results. Kinda like making glass, there's a procedure for that, but what really happen at the molecular level is still blurry.
With time the student's body and mind change and he gets skilled at it. How does he explain it ? does he have words to communicate his feeling to a newbie ? Never seen so so far. Recently some violin teacher was praised because he discovered non-linearity (the fact that inertia in normal speed gestures is not the same, thus learning technique requires you to fake inertia by allowing acceleration at slow speed, which means exaggerated movements). Still a shallow discovery to be honest. It doesn't really describe how to create and sustain this kind of inertia between multilimb chains and how to attempt it pleasurably.
Back to code, similar issue is present when one of the most effective (and pleasurable) way to learn the art is by pair programming (with a mentor or even a same level pair). It shows that some notions are still not taught properly in schools. Maybe the system is already at peak and there's nothing to change that would lead to better progress.