I just came across the phrase -->political affiliation as a team sport<-- to describe the over-polarisation of politics today and I think it really hits the nail on the head.
Many people, (esp men) are from an early age indoctrinated to feel they have to identify with a particular team in a particular sport as part of their identity, and this makes them vulnerable to also seeing politics in this way instead of looking at the issues and policies, problems and solutions.