There's politics, and then there's politics. The topics that get flagged usually are ones for which it's near-impossible to have a productive discussion. The HN guidelines are spot-on with "If they'd cover it on TV news, it's probably off-topic." The important topics usually filter through here. If you want to indulge in shouting at each other over what outrageous thing some political figure did or did not say this week, there are plenty of other venues on the Internet which encourage just that.
I've seen, and very occaisionally moderated, productive discussions on difficult topics. It's not easy, or pleasant. It requires firm rules for participation, and a steel will on the part of the moderator. People will be (or act) hurt. And in any sizeable discussion, many comments will be moderated out. Preemptive moderation (hold for publishing) may be necessary.
This isn't something HN are likely to entertain frequently, but I can think of a few topics for which I'd like to see the attempt made, perhaps every few months, on a scheduled basis.
