Or on my brain, rather. I'm not surprised that this graphic came from The Rachel Maddow Fan Page.
Why wouldn't it be a solution? Think about it for a second. If all those other responsible, law-abiding children on the playground had rocks to begin with, would the child in question still throw the rock? I think not. It's actually a pretty good solution. Sure we could threaten the naughty child with detention if he/she goes through with it, but then that poor other student still gets a rock upside the head. If we ban all rocks on the playground, then only children who don't obey the rules will have rocks...and not be afraid to use them. This seems much more preventative.