That's not really fair. At the younger ages those teams can be dominant especially on the boys side because they have a large recruiting base from various neighboring areas where they can pick kids off before the clubs get to them. They tend to recruit older, taller kids and can perform very well with that. On the boys end, various teams placed highly in state cup while CalSouth was still a vibrant thing. Problem happens towards the end of middle school where the high performers looking to play pro or college start looking at other options because AYSO is locked out of letter league.Paying Club fees to play AYSO teams? Doesn't sound too ELITE. lol
Yet, you have clubs like the Red Bulls on the boys side which despite having no proven track record were offered MLS Next over several other clubs of various trackrecords. When it comes to the highest level of letter leagues, if you build it, they will come, as is evident if you look at kids going to those teams that can't even dress for games, that are lining up to play even for the worst team, or that are willing to play third keeper.
You have various clubs, mostly larger, that control the highest level leagues, and everyone else is pretty much frozen out, and as a result, will usually lose the best of the best of their players.