This is a reminder that account karma on Reddit and Hacker News doesn't really mean anything and doesn't make your posts more valuable, or give it any additional benefit in the algorithms. (I say that as someone with 153k Reddit karma and a user ranked #57 on the HN leaderboards: https://news.ycombinator.com/leaders )
Going truly viral on Reddit/HN is still ultimately random as well, which is why reposting (within reasonable amounts) is allowed on both platforms.
As someone who works on social media automation/tooling for their day job (2018 rough overview of my work: https://tech.buzzfeed.com/how-were-building-superpowers-for-... ), I do agree that ML/AI can be helpful to aid human curation, but definitely not a magic end-all-be-all that growth hackers nowadays want it to be. Simple heuristics can be very powerful as well.
HN bestows various abilities once you pass certain karma thresholds. It's the only site I know of that does this and I think it really helps keep a better community.
It's a direct counterexample to the other comments saying karma is meaningless and isn't or shouldn't be used as a proxy for trust. It might be misplaced trust in some cases, but it is trust nonetheless.
The highest threshold for unlocking features HN is at 501 karma (comment downvoting), which is not a lot and is mostly there to limit abuse.
More importantly, it doesn't affect the submission ranking algorithm at all.
More seriously these posts got me interested in what features besides downvoting would be added at various karma levels which led me to your git page on the topic. Linked here for others interested: