If people don't like something, I think the motivation to act is more than if they do like something or are neutral. Human nature.

People will downvote a headline with positive comments on something they don't like.

But what do they do with a negative headline about something they don't like ? I guess they will upvote it to show they also don't like it.

So negative wins.

"ran GPT-4 sentiment analysis on full article text." I think most people vote based on headlines, not on article text.