Additionally, I think you need this rule to deal with some potentially weird situations.
Runner on 1st. Ball is popped up to the first baseman. Runner tags and br makes it down to first with the ball in the air. F9 loses the ball in the sun. When it falls the fielder thinks that if he hustles he's got a play at second and in his exuberance throws into the third base dugout.
Dead ball, runners to second and third. Now suppose it's a close game and the runner on first is faster so the coach sends him to third instead of the other runner. This is the rule that prevents such a travesty, isn't it?
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Children prilosec