Both, and that's what makes the question hard. The best comments I've read - on Hacker News, in niche blogs, in obscure forums - have changed how I think about things. The worst are designed to make you feel surrounded by idiots or enemies. The difference isn't the format, it's the incentive structure.

When platforms optimize for outrage and engagement, comment sections become tribal warfare. When they reward depth over heat - consistent moderation, voting that surfaces expertise rather than emotion - they can be legitimately good. Most comment sections are catastrophically bad by default, but that's a design choice, not an inevitability. The fact that we've mostly made the wrong design choices doesn't indict the concept.