I initially loved the idea of voting posts up and down. Thanks to seeing how it actually works on SO and here, well, I am not much of a fan anymore. At the very least, if I ever implemented it myself, I'd require that people explain why they are voting up, or voting down, before they could vote. And I'd not limit users from being able to vote until they magically get to the right amount of "karma". Without requiring…
Yeah, I really wish that HN required you to comment in order to downvote. Or even just required that a comment had replies before it could be downvoted; I don't care so much that every single person justifies their downvote as that the person getting downvoted gets an explanation.
For well-intentioned posts that are factually incorrect, it seems that there are usually replies that explain the reason for the downvote. When a comment is wrongfully banished to the grey nothingness, oftentimes others step up and defend it. The community immune system functions well as is.
Also, I adore the fade-to-grey side effect of the downvotes. It’s like spritzing a cat with water for scrounging on the counters—an ultimately harmless but super effective reprimand.