[buboard]

That is an important point but kind of orthogonal to P2P. A popular P2P website, say DTube could delegate its moderation to some group of "censors", and have some of its listings removed. Besides, unmoderated spam/trolling-infested sites are not going to become very popular anyway. Now you surely can't completely remove content that has been distributed but you can condemn it to be forgotten. 'Organic' forgetting may actually be easier in distributed web because sharing of content is generally temporary - just like you can no longer find older movies seeded in torrent sites.