I'm also not sure about your suggestion. Yes small polities had the means to defend themselves, but the pharaoh's army is much larger and you're definitely going to die if he shows up and you fight back. So why wouldn't the pharaoh have shown up to put down a rebellion? Time and time again in the history of the region a king, pharaoh, or other despot would make examples of rebels, put down rebels, and march armies up and down the region to ensure fealty and assign minor lords to protect a region. They could have found the smelters and destroyed them or seized them, those working on it could have been killed.
I'm just not sure that this democratization of violence is the answer. Though it may be a key contributor. Curious about your thoughts or others. Incredibly fascinating topic.