Because people weren't so dumb. If I grabbed a gun and did dumb things with it, &^% would get real very quickly.Nobody ever got shot.
There are no real guns in my house now (no license, no need for them, my wife grew up in the city and doesn't want them, I don't have a big enough safe, etc) but even when my kids are playing with nerf guns I give them crap for flagging people without eye protection, keeping their finger on the trigger, etc..
Not being a dumbass is pretty easy if that is the path you want to follow. If you want to be a dumbass, banning thousands of pages more long guns will not impact a single handgun crime (which is almost all of them).