One way to stop this would be to have people who post low-value high-expected-karma-yield posts get randomly banned. This would function as a variable punishment and should be quite effective at training HN users.
A better way to improve content quality would be to stop using karma altogether, but I understand that's deeply baked into the culture, and probably not likely. Removing the visibility of karma scores might be an adequate compromise. Upvoting, downvoting and sorting would work perfectly fine without the temptation of a score.
Hacker News has enough passive aggressive attempts at operant conditioning as it is - the fading of text posts to discourage "blogging" is one egregious example. If you don't want people to farm karma, get rid of karma. If you want to expect more quality and better engagement from users, treat them like people and not like mice in a Skinner box.
It's basically a linear prediction model: someone who behaved reasonably in the past is expected to continue doing so. This is not always true, of course, but I beg anyone suggest a more precise model that can be realistically implemented.
Another purpose of karma is preventing a bot from registering 1000 accounts and using them immediatley for insistent mass downvoting. Of course, one can build rings of bot accounts that upvote each other to gain karma before operation, but this takes much more determination and skill than an internet hooligan usually possesses.
If you have to have karma, you could attach it to comments (so indirectly, rather than directly, to accounts) and get a better overview of a user's behavior from the ratio of upvotes to downvotes. If it's necessary to have privileges like moderation be subject to some kind of test, surely some number of ok comments would be be better as an indicator than than an arbitrary karma limit?
Although given that Hacker News has literally no guidelines for voting, even that might not be a great predictor.
Also, ISTR mentions that HN employs voting ring detectors, and punishes detected voting rings to avoid exactly this phenomenon. So, its not just the passive difficulty that is an issue with this approach, there is active opposition.
EDIT: like how this comment is being silently downvoted now. I would like to think that the HN community has a wicked sense of humor.
But then there are people who silently disagree via downvote. To that I ask what the purpose must be. "I think you're wrong" - How? Why? Is it my tone? Lack of evidence? To me, downvoting without explaining is just a smug way to feel less insecure about one's own opinions without having to stand up for anything.
I wish downvotes here could be only cast with a comment explaining the reason, to improve clarity.
1. It contributes nothing.
2. It's a pop culture reference.
3. It comes from an HN brand that can be reliably expected to farm karma basically anywhere via name recognition alone.
