re: Why is the country/this board so polarized?

Of course it is. I was a more or less a centrist most of my adult life but have been constantly demonized by the left that it's impossible not to be turned off by the Democratic party. I actually agree with quite a few political philosophies of liberals but they're so busy blasting and demonizing me for not buying in to everything they believe that it has soured me on the Democratic party. Conservatives certainly aren't perfect either but they at least tend to respect the fact that Democrats may not see things the same way as them. They respect (although they strongly disagree) that liberals have every right to express their political views. Democrats often become outraged that someone dares to disagree with them and they act like those that do not agree with them have no right to a different opinion.