I agree humans will always make & keep weapons. But not all weapons are created equal and one can do much more damage more rapidly with an AR - whatever, than one can do with a knife. Students/citizens in Australia and France have fought off knife wielding assailants with backpacks. Can't with guns.
I can do as much harm with a hand gun as an AR-15 as both are, unless modified, Semi-Automatic firearms. AR, to be clear, means Armalite Rifle and not assault rifle. Yes the 5.56 round is nasty...but a .45 ACP Hollow Point can cause equally traumatic wounds.
The AR-15 has a mythos that is being used and blown out of proportion to what it actually is. And any regulation needs to be done with out emotion. Because when you regulate by feels, you make things worse. That is what I am saying.