True, but there is a second part to that.
In the absence of weapons, the large and predatory will have the ability to enforce their will against the smaller or weaker, and take what they wish.
You only are able to maintain your body, property, home, and family against the predator if you are able to meet the threat of force with the threat of force.
The police can investigate and prosecute the offender, but they cannot prevent the offense. Only a citizen able to meet violence with force can prevent the victimization.
Again, as in the thread with TSA issues, the issue is not dangerous things, it's dangerous people. Dangerous people are dangerous, with or without weapons. Non-dangerous people are not dangerous, with or without weapons.