HN doesn’t optimize for addictive. Fortnite and wow do. No opinion on NFL, but they probably do at least somewhat.
I think the term addiction is way overused in this stuff. If a company makes a product you enjoy using that doesn't mean you can just describe it as addictive and get out of jail free. If there's some chemical in it that messes with your brain, fine, otherwise people need to take ownership of their own choices.
I think the disturbing reality is these countries are wanting to control social media to control the population politically. There was even a Labour MP in the UK who admitted it on television. If it weren't the case they'd just tell concerned parents to turn on the parental controls devices already have, problem solved. Instead they pass laws to end internet anonymity, but only on the big networks, which won't do anything for kids but is an excellent way to control political discontent.
The current alternative is that unaccountable private interests control this, so some regulation in this regard seems reasonable to me. However, swapping private control for public control is only barely better.
The best solution that I can think of is ending algorithmic feeds, and having subscription feeds, or maybe user curated feeds, only.
I do agree that karma increases addictiveness and adds little value; I can see it being useful for certain permissions (so new accounts can't do thinks like downvoting), but it could just not be visible to the user; then there's no motivation to "increase my karma"
Can you please elaborate on what you find useful about thread-ranking? It's an anti-feature that only serves to increase addictiveness (by making top-level comments into a competition) and make it impossible to reload an active discussion and find your place again, in my opinion.
(I do see your point about not being able to keep your place, though I don't systematically go through all comments in a post -- or very rarely -- more just quickly browse for things that catch my attention, interesting info, etc.)