You certainly have a point here. When I was in high school I could spend exorbitant amounts of time debugging stupid errors caused by inexperience. I could read programming books, play around with code, build completely useless stuff just to learn, etc. for entire months. Now that I work for a startup and am a full time student, I only dream for that type of time.
Though, I think there is a pretty fair trade-off between time and understanding. I can pick up new skills (non-technical included) in less than half the time it would have taken me at 14. I've learned how to learn. Shipping an app at 14 is impressive not because they were able to do something difficult, but because they were able to do something difficult with much, much less life experience than is expected. This is to say that, although they have more time, it is, in general, more difficult for a young person to learn how to program. That is why I'm impressed when I see a 14 year old ship.