Science is a fact of life, one which nobody can really afford to ignore. But a steady diet of science news is bad for you: You are what you eat, and if you eat only science reporting on fluid situations, without a solid textbook now and then, your brain will turn to liquid. Or so I've heard.
Matters of policy and governance and economics are important. But typically, "politics" tends to mean "political news" -- election horseraces, poorly-designed opinion polls, and general show business for ugly people. That's why it's the mind-killer.
I would not automatically downvote a serious analysis of policy or governance on this site. Something like an examination of a RAND study.
Sure, valueless political discussions are valueless, and valuable ones aren't. Of course.
The question is whether we {do, should, can} condition our rejection of a discussion on its valuelessness rather than its political character. The implicit suggestion is that rather than treating political discussions as something special, we ought to enforce the general rule of rejecting valueless discussion.
The main difficulty I see is that we don't actually seem to enforce such a general rule.
There is a tendency to downvote articles and commentaries with a political subtext with a remark on how politics is the mind-killer. I completely understand that nobody wants his mind to be killed, however, I disagree on the employed methods. I don't think anybody can really afford to ignore politics. It's a fact about any group of even a handful of people. Thus instead of shunning politics I think it's better to build one's rational defenses. Understanding that politics is a problem is only the first step. If you stop there, there will always be a big part of life where you are not rational. Therefore I suggest that, as long as it doesn't get out of hands, there should always be room for political discussions if not on the main site at least in the discussion section.