Sad to say, but I get it... Sometimes kids can be pretty reckless with baseballs, or soccer balls, etc. In a crowded park, much smaller kids or adults can get hurt with a wayward ball. Kids aren't the most situationally aware.
But at the same time, my childhood was filled with schoolyards, and parks, and vacant lots; balls and bikes, and secret forts; water fights, and hide-and-seek in the evenings, and all kinds of mayhem. What a wonderful time to be a kid. Makes me sad when other kids don't get to have the same experience.