I would think that selections for YNT teams must be so difficult due to our huge population that a potential Messi that's never selected could get discouraged and quit aiming high. I also think the cost of soccer and good shoes, private trainings, physiotherapy, etc would be a barrier for many players. I also wonder if potential Messi's aren't challenged young enough. In other countries 15/16 year olds are playing and training on pro teams. Here I think that you need to be 18. However, even if girls couldn't they wouldn't because they feel like they need "exposure" in DA and ECNL because they are all chasing a college scholarship. And I don't think people even consider style of play or quality of coach when choosing a university. They just want the Div 1. Kids are being developed in the US. Maybe not in every town.
That's (YNT) an interesting theory; could be some truth in it. Cost is definitely an issue imo. But I'd say it's more logistics that are the barrier. If kids can go right outside with friends, walk to a close park, or play on the street, that makes playing soccer much more accessible, but today it seems that every parent has to shell out hundreds of $$ starting at the toddler age for classes, etc just for their kid to get some touches. The culture should be one where the kids are playing at home or very close and don't have to rely on their parent to shuttle them 1/2 hour to the pitch. Most latin countries have futsal courts where we normally have basketball courts, so, much more local access to play (ie more efficient logistics).
We should produce a Milner, then a few dozen more... https://thesefootballtimes.co/2015/01/15/can-mls-produce-its-own-lionel-messi-no-it-cant/
There is so much more to Messi's game than dribbling. His off the ball movement and field mapping are unparalleled. Messi's true super power is his immense understanding of the game and spatial awareness.