I usually use HN to research controversial topics, but i'm seeing little here about ivermectin and I've noticed a few ivermectin posts have been flagged.
Depends on what you mean by little. <a href="https://hn.algolia.com/?q=ivermectin" rel="nofollow">https://hn.algolia.com/?q=ivermectin</a> It's definitely not flagged as a topic itself.
It's allowed, but I get the sense that many HN users don't want it to come up to be discussed in depth, because it's a huge can of worms, because if it's established that it works, intellectual honesty compels us to ask why it was suppressed, and a lot of people would have their fundamental assumptions challenged.<p>I think that's why the hivemind often finds it convenient to just squash the topic by flagging it. Nobody knows who did it, nobody has to provide any reason for doing it, etc. Flagging is very convenient for suppressing discussions where we might actually get something done.