That depends on what we mean by "successful." The early chans were very moderation free -- 4chan initially didn't censor, then they started censoring furry content but not pedo content, then the furry ban got removed, then the pedo ban finally kicked in, and they've had more censorship since... but the initial seed was practically not moderated, and most of the moderation that has been put in place since seems like a result of legal fears (the brief furry ban being an obvious exception). The bitmessage chans are still moderation free, and will be as long as the bitmessage network has nodes, but of course that can't scale (for anyone unfamiliar, every bitmessage node tries to decrypt every message -- this means that there is no need for metadata concerning where a message was sent to, and since packets are forwarded across the network you'd have to be running multiple nodes to even guess where a message is coming from, but there's no way that everybody could recieve and try to decrypt everybody else's messages if the whole world used such a system). I'm not arguing that I want a system without moderation, just that such communities have existed, have grown, and do exist. My ideal would be a community with opt-in/opt-out moderation, but I also don't wish every community to reflect my ideals.