I have read his work, and also am friends with many university and conservatory music teachers who have know some prodigies. I'm sorry... you're wrong. The world is full of thousands and thousands of musicians who had 10k hours perfect deliberate practice from age 3 with world class teachers and don't become those people. Do they become great musicians? sure! Do they become the Pat Methenies? very very rarely. Even among jazz elite, Metheny is known as special.

And there are also has many cases of people who did not have any of that perfect-practice upbringing and and have aural awareness that is on a completely different plane from regular people. I know some of them (I'm doing a Master's in Music Tech right now). I know folks who, without the proper years of deliberate practice, are able to do things I and 99.99% of musicians will never be able to do. That does not mean they will necessarily become famous or have great careers, but they can do shit that is out of this world. One of Canada's best jazz musician's recounted to me chatting after a masterclass about music cognition how he had a college student who came to him for her lesson and could remember EVERY SINGLE NOTE of Keith Jarrett's concert the night before and play it for him. That shit is not normal, it's crazy savant stuff. From what I have read, Metheny was in that category.

Music is a funny thing, deliberate perfect practice is obviously the most important thing, but there absolutely are geniuses who do not have the same brains as us, and the top 0.001% or whatever has a lot of them. Savantism occurs (relatively speaking) often in music. If you want a counter balance to Ericsson's "practice is everything" stance (and there is lots of excellent material to take from Ericsson's work), I suggest reading Oliver Sacks, "Musicophelia", about the music related clinical stories from his career as a neuroscientist.