The same is basically true for most other sports in the US too, and yet there are still high-level Americans. Certainly baseball (which other countries do still play in a limited fashion), hockey and football. With football we are undisputed world champs for the last 60 years! Joking aside, there is no doubt that high-level NFL players are seriously talented and their whole sport revolves around structured practices and weekly games.
Basketball might be closest to the USA’s soccer – lots of unstructured play and selection to schools and academies at a young age, but historically the pay to play travel circuit plays a big deal there too, and American basketball players are no doubt internationally competitive.
I don’t have an answer either, I just think that the way we play soccer isn’t limiting the best potential players. I just think the best potential players are choosing to play other sports.