you can network, dm, and users who post frequently are often recognized here.
you can doom-scroll as much as anywhere else whether it be in the feed or in the comments (so long as you don't have a bias towards different mediums like video).
and also while it might not meet your criteria for social media algorithmically or otherwise, an algorithm is not necessary for someone to engage with the internet in unhealthy ways. the surface area for emotional damage is just different. and that doesn't imply HN is some special place where the only users engaging here are "emotionally well" in both their engagement/usage, and in their personal.
and speaking as someone intimately familiar with relevant behaviors and presentations, the algorithm exerts influence and exploits, but it is ultimately not the RCA -- it's just like a drug dependency for someone with maladaptive coping mechanisms -- the drug isn't "the problem", it's a symptom, and the "drug dealer" is taking advantage of it.
side-thought:
it always makes me wonder if people manufacturing and distributing what i see as a "need" for social media, while employing HOOKED marketing dopamine strategies to establish said need in its users, ever ask themselves: is this a net-good? should i be doing more with my life? is this harmful?
imagine being a demonstrably great mind and seemingly great person, but working somewhere like FB or IG or TikTok and applying every ounce of your intelligence to maximize user engagement.