Twitter, on the other hand, will have me doomscrolling every single time.

Twitter, Linkedin - I don't have the same problem. I post something (when I remember, which isn't often) and then forget about it. I can go weeks without checking LinkedIn. I tried Instagram and just didn't 'get it'. Reddit annoys me. TikTok scares me - I tend to avoid mirrors at the best of times, so the thought of short video clips of me floating in the aethers ... it's never going to happen.

I'm probably a little addicted to HN; I have no desire to cure myself of the site just yet. I'm not convinced that blocking the site in my browsers/devices would help me if I wanted to cure myself - I'd probably end up spending time trying to subvert the blocks (as a learning exercise, of course).

I've unsubbed from most people and keep my friend list extremely slim (less than 200 people over ~10y of usage, with extensive pruning). Its basically a news aggregator for me, and additionally a way to connect with the communities I am involved in (which are niche (home) brewing groups). The groups are surprisingly untoxic but that's entirely down to the awesome moderators and the scientifically minded people they manage to attract.

I think the usage of mostly real names also helps knowing the people better than just some random nickname and knowing where (if even) they work.

I find places where I leave comments (like Reddit, or HN, but Twitter also works this way) a lot worse for this "addiction via narcissism" aspect. On these services, your post/comment doesn't only get more and more popular; it may also be rebutted by a reply (not necessarily made in good faith), at which point it might start getting less popular, possibly dipping into the negatives if the reply's reinterpretation paints you in a bad-enough light. Because of this, there's a feeling of having to watch for these replies, and leap to defend your post against them, so that the reply's interpretation of your words doesn't "win out" against your own actual meaning (which may not always have been perfectly clear from your original, succinct wording.)

That's "narcissism" too, in a much stronger sense of what Narcissistic Personality Disorder means: the obsessive paranoia over losing social capital, due to being perceived as having committed a social faux-pas, that leads one to avoid taking social risks, and perhaps even lying to make oneself seem more "middle-of-the-road" within one's social cluster than one actually is in private.