Can you point to a single story since the inception of Hacker News that quite obviously involved the intersection of hacker/startup culture with the rest of society where politics were not discussed? What is any discussion about wealth or economics if not politics? Is it a vanishingly small percentage of PG's essays that express a strong political opinion?
As far as I'm concerned, discussing politics as they relate to hacker culture is on topic. Discussing the Boston Marathon bombing, not so on-topic, but nevertheless people here had interesting things to say from a hacker perspective. I'll be the first to agree that political extremism is aggravating, but the solution to political extremism is not the avoidance of politics altogether.