You ever been bashed in the head with a brick?
Thank you very much. There were several soldiers in Bosnia who were hit by flying bricks and boards and much damage was done to them. Anything can be used to kill if you put enough thought and muscle behind it.
I was bashed in the back of the head with a bottle, knocked out and then fell into a curb. It resulted in a severe concussion, broken tooth, cracked rib and 6 stitches to close the head wound. I got lucky.
I am 50, 6 foot and 200 lbs, trained in the martial arts and recover fairly well from injuries. I brick (rock) is known to break bones and crack skulls for even healthy adults. Kids and elderly can easily suffer broken bones, or even be killed.
Overkill? Not in my opinion. A deadly weapon is a deadly weapon, be it rock, brick, stick, pipe, knife or gun.