Hammers don't drive nails...

...but have you ever tried to pound a nail in without a hammer? 

And screwdrivers don't turn screws.  People turn screws.  With screwdrivers.

Yes, you can pound a nail and turn a screw without those tools.  But they are designed specifically for those tasks.  It's what they are for. A hammer is the most efficient way to drive a nail.  A screwdriver is the most efficient way to turn screws.

So I can't imagine any stupider argument against gun control than, "Guns don't kill people. People kill people."