MakeAPlay
DA
At U12/U13/U14, it's true that no college scouts are watching (unless they happen to walk by between games), but it does raise your kids' profile in the eyes of his or her coaches, who sometimes take kids for granted until someone else spots them, and you get some credibility in tryouts with Academy and other clubs if you're interested in that. This is particularly true if you're the only player from a middling local club, since there's little chance your coach/technical director pulled strings to get you on the team and there's also little chance other coaches are going to assume you must be good on club name alone.
None of that is really the reason to do it, however. The benefit is playing with strong players, often at a different position (a lot of center midfielders end up playing outside mid or wingback on an ODP team), with different coaches and against teams from other states with different styles, some of which are good and some not, but all generally opportunities to learn. The goalkeepers, especially, are getting college GK coaches warming them up during every training and before every game and offering technical and tactical instruction, usually for about 30-40 minutes. Most GKs get none of that before games with their clubs.
Is it worth the time/money (not much, but not nothing if you are traveling to watch your kid)? It has more upside and opens more doors than guest playing at an out-of-town tournament, which lots of people do despite the cost in time and $. You're not likely to get an invite to a USYNT camp because of ODP, but it might help you get better/get opportunities to advance. Kids also like the feeling of pride representing something bigger than their team or club when they play for their state/region.
Does that mean they pick the "best" players? Out of ~7000 in an age group from San Diego to San Luis Obisbo? Obviously, there are tons of players who are overlooked. Even those parents who think they know who the "best" players are, base that on the best teams in the best leagues/tournaments and likely miss a kid from a middling team that isn't at national cup where they scout players. It's not really all that different from Academy. You have to be in the right place, at the right time, and even then you might not get selected or invited back. Probably the biggest thing is to be humble about it, because both DA and ODP have become diluted over the years and even when they really were rare opportunities, they missed kids and made odd choices.
Most of the kids in SoCal got their first call ups to YNT teams through ODP.