Pull a trigger in the air without a gun, and see how many you kill.

The gun is an extension of the user - without the gun, you cannot shoot, just as without a person the gun won’t shoot.

Same is the case for words. They didn’t come out of the aether into existence, and when spoken carry the will of the speaker inherently.

It’s not “just words”, it can be malice or hate given form - that is, after all, the point of communication; to give form of what you desire or think to others.