This is truly one of the best moderated places on the internet IMO, and one of the only places after 20 years of posting on message boards that I can go without hurtling toward a flame war every time I log on nowadays. Part of it is, I'm opinionated and I think probably enjoy arguing more than might be reasonable sometimes. Another part though is that the moderation quality is so high here and so low on places like Reddit + Twitter. My 2 pence.
Probably the lack of ability to advertise here the way you are encouraged to do on Twitter/FB/IG/Reddit (because they need that revenue) factors in as well.
One of the things I appreciate about HN is that I can still read the posts that are removed (with showdead enabled).
I don't care much about my freedom to speak. My voice will never be a significant influence on the world anyway. What I care about is my freedom to listen. I value the freedom to review all the evidence and all the arguments then draw my own conclusions.
I don't often want to read dead comments. They are mostly low quality and deserve their status. Nevertheless, showdead is sometimes quite useful and the transparency gives me more faith in the moderation.
that's part of the reason why I come to HN, for well-moderated (or "censored" if you prefer) discussions on tech