People seem to find it much more entertaining to be an asshole and say that anyone who disagrees with them is a moron than to try and empathize with those who disagree.
That's one aspect of it, to be sure.
The other aspect of the matter is that we now have ideological parties. All the conservatives are Republicans these days. All the liberals are Democrats. It's easier to talk trash about others when they're of the other party. It's harder to do so when the conservative blocking liberal legislation is part of your own Democratic caucus.
