It seems that you are focused on the kids that don't make it in HS that played travel. All I can talk about is my experience and what I have seen in my sons HS. The coaches don't have time for projects. If you don't get it done on the field their are 2-3 kids that will. Some HS's are different. If you show up you make the team. Not my sons team. The high end travel guys don't have time for projects unless they see insane talent. If you are starting at 13-14 to play high end ball you will not play high end ball. Period. You will always be behind the curve playing for lessor teams and lessor coaching. You may catch up by the time you are a junior or senior, but it is going to be tough to break into a line up and the kid is going to have to be awfully hard to put up with years of being cut. It does happen, but it is very rare. Why would you want to give your kid less of a chance, put him at a disadvantage when you don't have to do it?
Why would you want to say no to your kid if he wants to play against the best?
Why would you want to have your kid less skilled than he can be? What is good about that? How does it help? Just because you have good skills and play high level travel doesn't mean you are done growing and getting better. I see kids with great talent working their hineys off to get better. Grinders with incredible ability. This is what my kid competes against.
There is no advantage to waiting to get high level competition and coaching if your kid wants to do it. Why wait?