It's a procedural point, not a political one. Comments like the one above provoke inflamed responses from people who disagree with them, and vice versa, creating a cycle. Each time a provocation lands, the person who gets smacked (not really, of course, but that's what it feels like) feels justified in smacking back harder. On any divisive topic it's guaranteed that quite a few users will feel that way, so the threads are doomed unless we all contain ourselves in the first place.

This isn't a bad restriction to impose, because ranty provocative comments are nearly always less substantive, and we want substantive comments here anyhow.