I don't see any technical difference? On HN, you scroll through an algorithmically generated list of submissions, vote them up and down, and post and vote on comments. This is pretty similar to FB. Just replace "cat videos" with "pelicans on bikes".
Basically I agree with your second point. I'd been hung up on the notion that people were maligning specific technical choices (and indeed there are sub-threads where this argument is being advanced), but that's not the case here. Y Combinator's goal with HN is to make money indirectly, by discreetly, almost implicitly advertising itself as an outfit at the centre of things of interest to the "higher end" of the tech field, who might then (a) absorb awareness of it by osmosis and later (b) think of it first when planning their next startup. As such its goals are much more closely aligned with what that crowd enjoys, than with maximising engagement and thus eyeballs on ads.
Everyone being served the same algorithmic results is a genuine technical difference (I believe; do we actually know that HN doesn't customise the front page for logged-in users?). I think it's quite a fine distinction, though -- both sites are trying to hold the user's attention, one just omits to use an available level of customisation. I have no moral objection to either approach.
I think it's half culture, half being text-based. HN is heavily self-correcting when it comes to low quality content, trolls, spammers, clickbait titles.
It feels very healthy how I can choose what to engage with, and what to ignore.
That's just your bias talking, though. Of course different people are going to have different opinions, but Facebook users feel the same way about Facebook, TikTok users feel the same way about TikTok. Anyone who didn't feel that way wouldn't use it.
I don't entirely understand the point you're making, but I disagree with the last part. People not only have different needs from the media they consume, they also aren't equally rational with how they decide what to consume.
talking about doomscrolling and how it would be better not to do it is one of the favourite pastimes of the doomscroller. loads of fb users hate it but struggle to believe they could do without it.
It's interactive. As in, we write and talk, often about articles posted. That's completely completely different than passively absorbing content spoon fed by Silicon Valley algorithms and sweetened with graphics, attractive people and sudden music and sounds.
What's the point though? I'd like to think scrolling HN is healthier than Facebook. But is it better than curated subreddits, or Instagram/TikTok showing you stuff about your friends and hobbies?
I don't think it's pedantic to have a bit of self awareness, although engaging in the discussion instead of writing a pithy one liner would be better.