He is not playing to you, you are not his audience. This is like asking "Why are all these dicks flopping about in this gay porno?"

That is what most people don't get about American culture. We don't vote upon issues, we vote upon slogans that strike a chord with our understanding of the world around us, usually significant historical events. It's not stupidity, like many are willing to dismiss it as, but a primitive call and response form of communication that is part of every human's psychological makeup. It's how we passed on knowledge before the written word.