I read through the comment thread there. There's almost no explanation of what's going on, not even the offending URL. When someone asked, he got downvoted a bunch and ridiculed, which reminds me of why I don't have a Reddit account. I don't trust archive.today because of its track record but don't trust this particular allegation either. The news is simply that a subreddit moderator blacklisted archive.today.
They've added a comment explaining what they saw, with the offending URL. It's indeed archive.today itself sending visitors to the malware download site.
No it doesn't. Aside from people here actually being curious about things, the site itself isn't designed for flame wars. It also makes it hard to get downvoted so much that your account goes into questionable standing. I'm guessing people on Reddit fix that by farming karma somewhere else, but no way am I going to bother with that.
FWIW it's quite easy to farm karma to get to the downvote threshold. If you go to any of the energetic political HN threads, you just need to submit an enthusiastic comment that is pro the dominant position and you'll get tens of upvotes quite quickly. Do that for a week and you'll be ready to downvote. Before HN had LLM detection I had an experiment with an LLM doing that (though I approved everything it wrote by hand) and farmed karma very quickly. I stopped because I felt quite gross about it, but realize it's probably trivial to do now.
The problem isn't really the site, it's the people. People like smashing the up and down buttons on things they agree with and unfortunately a comment's score affects where it shows up on the page.