One of the fundamental problems with most things on the internet is that there’s unlimited output. A socially dysfunctional shut-in living on the internet is simply going to have a much larger output than someone with a healthy social life that only uses the internet in moderation. Someone who is judicious about their upvotes is going to have a much smaller impact than some who just reflexively upvotes or downvotes everything based on kneejerk reactions. This becomes even more prevalent when you add gatekeepers. Most people don’t have time to be volunteer editors or moderators. Or to park themselves in the new submissions section deciding what should make it to the front page and what should drop off.
So of course anti-social nutcases dominate these spaces. That’s how these spaces are structured.