I never would have thought of this. It's kind of clever really, and unlike the running on a second strike, it doesn't break any rules. I prefer to teach them how to play for real than teach tricks, but I can't help but think it's a kind of smart trick.
I will paraphrase sluggers from another thread: They are making the mistake of building players to win a 10U/12 game instead of building players to win in 16U and older