The karma points you get on HN are worthless, which I think is a bonus. They don't buy you anything. On Reddit, for instance, many parts of the site are walled off until you have "farmed" enough karma to participate.
You get the right to down vote and if I promote my totally not a scam product on HN, people will check my user account and see: on wow over 9000 karma? Gotta be trust worthy, when in truth it's just been karma farming.
I don't know, never found much value in karma. I recreate an account at least once a year for no particular reason and it roughly takes me a week to get enough karma to do what is important (flagging posts).
You get the right to down vote and if I promote my totally not a scam product on HN, people will check my user account and see: on wow over 9000 karma? Gotta be trust worthy, when in truth it's just been karma farming.
HN does limit some of it, but it's not a panacea.