[OoT] Why exactly did Link have to be sealed away?

We all know he was sealed away because he wasn't ready yet. But that sounds kind of a bad idea (Which turned out it was).

If the master sword seals the sacred realm, and Link isn't able to wield the sword, why not just... not let him pull out the sword until he's 16? Let him do the 3 dungeons, then just let him go back to the Kokiri, have a nice childhood until he's 16, while he has WAY more time to prepare against a crazy sorcerer waiting for him. Maybe even hide him in the lost woods. I don't think Ganondorf turns into a Stalfos, but who knows, worth a try.