Is anyone saying that firearms can in and of themselves do anything?
Someone who is bent on killing someone (or a group of people) will find a way to carry out their evil regardless of the tools at their disposal. Japan has some of the most restrictive firearms laws in the world and to be honest they don't have a major problem with firearms crime, but they do have a problem with mass knife attacks (yes, it's a thing). At the same time Mexico also has highly restrictive firearms laws yet in spite of them the drug cartels have no problem obtaining them and using them to control entire populations of unarmed citizens.