You can't have a healthy online community without moderation. It gets overrun by spammers, trolls, off-topic conversations, and flamewars. Moderation is the reason that all of us are here instead of Usenet or 4chan.
They didn't say anything about 'healthy' though. Reddit, Twitter and Facebook have lots of trolls, off-topic conversations and flamewars (and spammers aren't that rare either), and yet they thrive.
Exactly. While in some ways moderation and censorship are synonymous, the intent is different. Moderation is necessary for healthy communities - online and offline.
