HN has a downvote button, but only for those who've engaged on HN for a bit prior to downvoting. It helps prevent abuse.

There's a significant difference - misleading/malicious content.

A fake trailer can for example be spotted by the number of negative votes. If the negative votes concept is gone, using a low number of positive votes as indicator is less effective.

HN does have a downvote button you just don’t have enough reputation to use it yet.

To be fair, you can downvote comments here, which is often used effectively. Comments with a high dislike count are even specifically highlighted.

i don't know. The more i look at hn the more i appreciate the thought that went into it. Stories are far more black and white- either they violate the guidelines or not. The only thing a downvote would do is to make the story float all over the front page as there is an inevitable vote war. I would even say that most users don't like any given news story, which would lead to the situation that everything would get downvoted into oblivion. Comments OTOH lend themselves far more to moderation by downvotes. Remember we still get the "nuclear option" of flagging a submission.

It is horrible, you just don’t know it it. There is always people like dang dedicating his life to fight all the spam. Look at “new” page and see how many dead links are being submitted each hour.

When you put dislike button, you are adding a degree of freedom in expressing an intent for the user. It is upto you, how you use this information. Most systems fail in this task and then they just remove the degree of freedom as their solution.

Hacker News has a downvote button, but you need enough karma to unlock it.

I assume this is sarcastic but flags on stories are a significant option.

Not too horrible but a bit annoying. Fortunately, HN is not that site.

It'd be a lot better, actually. Downvotes are social poison.

It would be MetaFilter, a site with a noticeably higher level of discourse than HN.