I believe this reflects more on you than the platforms. The phrase "Great minds discuss ideas; average minds discuss events; small minds discuss people" seems applicable to HN (ideas), Reddit (events), and Facebook (people).

That sounds a little arrogant, but is my general experience. I see this in the submissions and comments where HN demands thought out posts. Jokes or comments that do not contribute are rarely at the top and often removed, while the opposite is true of jokes on Reddit (in general)

Having been an insider on at least two topics where the HN comments section consensus is confident and authoritative-sounding and detailed but way off the mark, I'm beginning to doubt this. (Not going to say which topics).

The "avoid gratuitous negativity" policy has helped, but we are still very much in a place of "most negative opinion wins" which pushes some discussions way off of reality. And those are just the ones I know about.

Turns out that sounding smart or righteously indignant (or usually, both) doesn't make something correct. Just a weird rabbit hole of darkly gratifying negativity. I guess I'm waking up to the fact that our flavor of "discussing ideas" might not actually be that more high-minded than Reddit or Facebook.

I'm not sure exactly how to quantify it. I think you'd have to look only at public discussions of IT-related topics on other sites, since that's all that's in scope for Hacker News. Facebook suffers with a clunky forum system that doesn't do threading particularly well, so you end up with a "flat" discussion with a lot of duplicate comments. I don't have a lot of confidence in the "like" moderation system either. I hope that's not gratuitous negativity. Example: https://www.facebook.com/arstechnica/posts/10154966971473753