Kicks into the endzone: rationale

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The other day someone asked me, "How come the rules in high school football do not allow a kick to be returned from the endzone?"

My smart-alec answer was, "Because the ball is dead as soon as it crossed the goal line and you can't return a ball that's dead."

This person was interested in the rationale behind that rule ... and I had no answer (smart-alec or otherwise) to give him.

So, does anybody know the history and/or rationale behind the rule?