They're right about the intolerance, though. One tribe literally calls the other "Demon-crats", and has worked to reduce participation based on gender, sexuality and skin color.
The internet is awash with seething tribal hatred. It's impossible to honestly believe this is only an issue with the right. The "demon-crat" attack is roughly analogous to the left's "nazi" attack (nazis, after all, are the secular-progressive equivalent of demons, with Adolf Hitler being their Satan), and the latter attack is infinitely more common than the former, even on HN.
Both sides are at fault. Here in the Midwest many a supporter of the Democratic party are legitimately afraid of being fired if their support became public knowledge, while on the other hand in California (or other "Blue" states) it's the exact opposite. It's astonishing to see how much Americans relish oppressing their fellow citizens.