The down-vote feature (for those who didn't read the article: you have to provide feedback to down-vote) is something I've spent years saying HN badly needs. These days I just don't bother posting most of the time because while I shouldn't be bothered by abuse of negative rep; you can't help be pissed off when you've spent a short while including detail only for someone who doesn't understand the subject or has a per…
Downvoting isn't the problem - it's spam flagging. There's no better tool for suppressing ideas and viewpoints you disagree with than flagging it. Only on HN can a story occupy #1 on the front page due to overwhelming upvotes, and 30 seconds later be sunk to the depths of page 2 or 3 by a handful of flaggers who disagree with the content that's presented.
I get the motivations behind both, and in some situations it works great. But a lot of the time it helps to enforce a monoculture on the site: any disagreement, particularly strong disagreement, is seen as a negative signal and is vanished from the site. Next time you see a post about, say, women software engineers, you’ll be able to watch it happen in real time.