You can kill someone with rocks. We used to go out in the woods when we were young and place clay tiles at about 20-yard distance then we used to compete with each other in seeing who could shatter most amount of tiles in fixed amount of throws. Some kids were down right 'lethal' with their throws. Now imagine it is your skull in the place of the tile and then things will fall in perspective. No one can survive a rock hitting their head at the speed of 80mph. In the most optimum situation, you will be paralyzed for life. Why would anyone want to risk that instead of taking defensive measures? I would not and I do not expect anyone to stand by and take a hit from the rock. You stop being an innocent kid the moment you pick a rock and hurl it at someone.