I was born 20 years after this film's release and my politics are therefore a bi-product of the world these two men helped create. Before the opening credits finished rolling I'd already picked my champion, isolated the villain and noted which interview subjects to boo and hiss at. By the end of the film I was ashamed.
While the primary focus of the film is the Buckley/Vidal debates, the running theme seems to be a lamentation for the bygone days when journalism was about issues, not identities. Before complex scenarios where dumbed down to generic good-vs.-evil stories that actively discourage critical thought. You can see early indicators for even more damning material in the future, including Fox News, Breitbart, and even the Trump Presidency.
There are no winners in this debate. In the end, we all lost.