Regarding the bad faith actors, HN largely (to my knowledge) self regulates; users can usually smell a promotional-type post &/or comment right away. It's something that keeps me coming back daily compared to other forums that seem to either ignore or prefer this type of content.
HN is very well moderated through human effort and they consciously resist updating the site design which is good. The barebones appearance naturally repels people with different interests or temperament.
Cheers.