I don't think voting is related. There are some subreddits that do have quality content, but this requires a substantial moderation effort. The *chan sites are even worse than Reddit, and there's no user voting AFAIK. Slashdot had a voting system before Reddit, and the discussion there is mostly civilized. Usenet didn't have a voting system, and the discussions were civilized before Eternal September, when users generally followed a netiquette. HN itself has limited voting and civilized discussion, but the site could get overrun at any point if the userbase grows rapidly, and new users decide not to follow the rules. There have been Reddit-type comments here for a few years now, and it seems to be increasing.

So it's a matter of community morals and values, and laborious moderation efforts to sustain it. Once the community grows large enough, moderating content becomes unmanageable. All large social media sites struggle with this, as they literally can't keep up with the amount of content. This is a scale problem that is unique to the internet.