Why do Republicans think pointing out that the KKK was started by Democrats is relevant today?

It never hurts to know your history. The relevance is that parties can turn on a dime and if you're not paying attention you'll find yourself on the wrong side. If this election has taught us anything it's that the press on both sides lies to us regularly, and skillfully, with zero remorse. My advice to my sons has been vote your heart, and remember people are more important than politics. If you can befriend someone with opposing views, it's harder to demonize them for their beliefs. There are good people everywhere. In 1985 Bruce Springstein said, "Blind faith in your leaders, will get you killed." He was, and still is right.