First off, good luck trying to implement any kind of decentralized network service when almost nobody has a globally routable address. Second, if ISPs are will

First off, good luck trying to implement any kind of decentralized network service when almost nobody has a globally routable address. Second, if ISPs are willing to keep records of IP-address-to-customer mappings, it's not much of a stretch to add TCP/UDP ports to those records as well.