The only way you're getting a decentralised system without child porn at all is to allow some moderation. Decentralized consensus-based moderation can probably

The only way you're getting a decentralised system without child porn at all is to allow some moderation. Decentralized consensus-based moderation can probably be relied on to shut down child porn distribution, but soon you're going to run into the problem that large numbers of people signing up to use the service hate Nazis and/or BLM just as much...