Calling something a curve ball is not terribly helpful if it is used to refer to all "balls that curve". My son threw a "curve ball" from a very young age to go with his relatively high velo fast ball. He caused the movement with nothing more than grip change and finger pressure - none of the twisting motion associated by most with a curve ball. Many well intentioned parents (most of whom were strangers to us) approached us at tournaments to warn us about the use of "curve balls" at his age. I am a firm believer that traditional curve ball have no place in the game for young pitchers - and if they are used (mine did not) - a few a game (5 or 6?) should be the max. A good pitching coach can teach a pitch that moves quite nicely to a young pitcher without endangering the arm. One pitching coach we worked with holds the opinioin that NO ONE - including pro's - should throw a true curve ball if they want to protect their arm. Not saying I agree - but an interesting opinion.
I, too, cringe when I see young pitchers throwing a traditional curve - but I also cringe when I watch young pitchers throw too many pitches of any kind - and get to little rest.
If all the parents that are soo excited about junior's success would consult experts on the appropriate care of a young pitcher's arm and then apply the information they receive - we would have fewer injuries. Remembering that the goal is NOT to win the LLWS - but to enjoy and have success at much higher levels - should empower parents to set limits. Like anywhere else - looking for immediate gratification in baseball can be costly in the long run.