This isn't a uniquely Republican / Democrat United States problem. It's a problem in the UK and and it's a problem in Australia and so likely in most Western Democracies.

Simplistic ideas presented with easy-to-remember slogans defeat any complexity because of how humans work. Very few voters have any understanding of the various issues facing modern society, so politicians can say whatever they want without really being held to account in any kind of realistic fashion.

As a meta-example, it would be easy for me to get on your Republican-bashing bandwagon, but the issues at stake are infinitely more complex than that. The Republican / Democrat divide is a perfect example of humans inability to process nuance outside their areas of deep understanding, which are generally very narrow if they exist at all.

We've got easily persuaded societies under political systems that reward the kinds of people least deserving of positions of power.

If anti-science wins votes, then anti-science it is!