There are certainly communities that &quot;explain&quot; the behaviors of mental illnesses in a way that don&#x27;t help people who are at risk but instead drives them even more into the illness - i.e. certain extreme conspiracy boards, esoterics sites or misguided bulimia &quot;self-help&quot; groups. For sites like that, I agree.<p>However, as for groups which just represent off-mainstream subculture I don&#x27;t see it. Well, technically they are of course &quot;contagious&quot; - that&#x27;s how transmitting culture and ideas work. But not every bad idea or weird subculture is already a mental illness. I would think &quot;sterilizing&quot; the internet by taking away all &quot;contagious&quot; sites would not just rob it one of its core identities, but would also present serious free-speech and censorship issues as the criteria for being &quot;sterile&quot; don&#x27;t seem clear-cut at all to me.<p>Or to make an example, many opinions on HN aren&#x27;t mainstream either. What would make HN a safe site to visit, but Tumblr not?