The median age of YC founders is 30. These aren't the pliable, simple-minded children of your caricature. Many of them are accomplished entrepreneurs who understand power law dynamics perfectly.

Further, I think nearly every founder who has gone through YC would report that, succeed or fail, they are net-benefited by the experience. Rather than stunting an individual, the exercise of founding a startup is probably one of the best ways to rapidly increase your skill-set over a short time frame.