Obviously on this site there are some harmful cases not involving open marriages. And while cheating may not be illegal, I'm pretty sure that many people would rather they be physically assaulted to a degree enough for the law to be involved than to be cheated on in a relationship they value.

So then the question becomes, how much wrong/harm can a site promote before it is shut down?

What about an anti-vaxxer site that is leading parents to make choices that will kill some number of children?

What about a website hosting all the leaked data from this hack?

What about a site promoting self harm directed towards children who are most vulnerable to such promotions?

What about recent Tor sites that were taken down?