I think one major problem is party politics.
If the Aardvark Party advocates wearing top hats, tickling toads and eating strawberry jelly for Sunday breakfast, then I might be drawn to them because I enjoy a good toad tickle and a weekend strawberry jelly. However, I might be ambivalent on the subject of top hats.
My jelly-eating neighbour happens to be a supporter of the Zebra party, whose manifesto decries all forms of amphibian interference and wants to ban top hats. We could either be glad that we have the jelly eating in common and sensibly discuss the pros and cons of top hats, or we could fight tooth and nail and decide that each other is a loathsome individual (possibly even "a mean-spirited, low-lived fellow, the son of a half-breed Indian squaw, sired by a Virginia mulatto father") because the particular party we support disagrees on the subject of toads and hats.
Party politics is divisive by its nature. It doesn't want you to feel sympathetic to the other person's viewpoint because it might consequently lose you as a 'customer'.
