It’s fun. 

 You’re right, it is 100% a psudeo-intellectual version of sports for them.

It’s not about what’s true, it’s about how they can plausibly slander everyone else in a way that stupid people won’t notice.

Then I, someone who went beyond the entry level polemic, come along and burst their bubble, hence the fun. 

 Sometimes it can be funny and entertaining. The ending is almost always the same and the patterns that lead up to the ending often follow the same trajectory though. It always seems to end with some version of: 'We're done here, good day, sir'. 

 I like being able to flex that I know easily accessible facts that disprove their entire worldview, that they would know if they bothered to open a book once a year.