If nobody in the world was manufacturing any weapons and it was fully observable from space, nobody would have cause to manufacture these kinds of weapons. We do not live in that world.
At some point, any reasonable person should agree that if a country exists in an environment that contains many threats it might need to defend itself or others from, then it makes complete sense for it to develop weapons towards that aim. Countries are not people, people are people. So people make the weapons.
It just so happens that Palmer Luckey is a person. He can't sell weapons to any random person or country he wants, he can only sell them to the US or with permission of the US to a country that the US has a strategic interest in defending.
Precision weapons have helped reduce casualties. This is a fact. Please try to contradict this fact in the face of napalm bombing and nuclear bombs of yesteryears. Please try to tell me that precision weapons aren't better than just randomly aiming artillery at the sky and letting'er rip. Please do. I want to hear your well founded argument for this.