It's worth noting that the actual enforcement of the norm-- downvoting of any comment remotely perceived as political-- is a dramatic enlargement of the recommendation actually made in that post.

I'm not saying that I think Overcoming Bias should be apolitical, or even that we should adopt Wikipedia's ideal of the Neutral Point of View. But try to resist getting in those good, solid digs if you can possibly avoid it. If your topic legitimately relates to attempts to ban evolution in school curricula, then go ahead and talk about it—but don't blame it explicitly on the whole Republican Party; some of your readers may be Republicans, and they may feel that the problem is a few rogues, not the entire party. As with Wikipedia's NPOV, it doesn't matter whether (you think) the Republican Party really is at fault. It's just better for the spiritual growth of the community to discuss the issue without invoking color politics.

Instead of merely downvoting the "good solid digs" and color politics people will downvote anything that even pattern matches with a contemporary policy issue. This, I would argue, actually exacerbates any political thinking because commenters then feel like they're being attacked and respond in kind.