How many Karma points do you have? (top right). I don't think I could downvote until I got to about 1000 or 1500 points, I believe.

I think you need over 500 karma to downvote. I couldn't downvote for my first few years here (and I probably only downvoted posts once or twice since I could)

The threshold is at 500 karma points.

My point was more that if you're being 'punished' for a comment, it's not the person you're replying to that is doing it - that is, it's not the person asking for the explanation that's punishing it.

I think that the GP is being unfair, though. Complaining about arguments specifically on the topic of politics? That's the essence of politics - conflict and how to deal with it. If people didn't disagree on a topic, it wouldn't be political. Outside of political topics, I'd say the bulk of explanations offered on HN are upvoted or at lest left neutral.