There is a difference between ignoring abuse reports and being immune to a raid by law enforcement. For these authors there is a trade-off between convenience, cost and security: using already available infrastructure is probably easier than to set up your own complicated hosting solution.
If any of them end up getting caught because of the information gathered by this raid they obviously misvalued one of these aspects in their trade-off analysis. Humans all make mistakes.
In order to keep a coherent network, most (all?) P2P infrastructure still requires some centralized resource to seed initial peers etc for a node. You would still have a single point of failure, if not for the network, at least for your control of it.
