Both sides have a fringe element (the left has the SJWs, the right has the alt-right), and each side tries to present the opposing side's fringe element as representing the whole. To compound this, neither side denounces their own fringe element.
I wish we could take the extreme / fringe elements from both sides and put them on an island somewhere. Maybe then decent folks from both sides could work together without all the noise.....I know, I'm dreaming....but I'm not giving up.