With content moderation, there are a couple different signals that are both important, but that shouldn't be conflated.

1) The comment is on-toptic relevant, and adds value to the discussion (quality).

2) Whether a user personally agrees or disagrees with the content of a comment (content).

Downvotes are a negative signal. There isn't a clear way to distinguish between "this comment is low quality" (quality moderation) and "I disagree with it" (content feedback).

Downvoting has the aggregate effect of suppressing speech. In the case of low quality, this is a good thing. In the case of disagreement, it runs the risk of discouraging expression and diverse ideas.

Perhaps people have ideas they'd like to discuss, but don't want to risk "losing points" because the idea may be unpopular. I know that I have personally experienced this, and stopped myself from expressing an idea because I've been pretty sure it wouldn't be popular. Given the overall high quality of discussions on HN, this chilling effect is disturbing. Have others experienced it?

Upvotes are a positive signal, it seems to me that the risk of conflating positive signals is less than that of conflating negative signals, since it doesn't have a suppressive effect, it has an uplifting effect.

Would it make sense, and improve the community, to eliminate downvotes and to only have positive signals?

To be clear, I'm not suggesting getting rid of flagging a comment, just downvotes.