I don't buy that NAT is a huge roadblock. A VPS is $5/mo, or dynamic DNS plus port forwarding is free. Either way, an ISP can apply the same reasoning and cut off access. Centralization due to using DNS (or raw IPs) for naming is the problem. Censorship resistance comes from there being a swarm that as a whole cannot be taken down, while members come and go. This requires a decentralized namespace for referencing content.