Re your question -- it depends: if the network ends up being based on Yggdrasil, as the blog post suggests it could, "IP addresses" are public keys, and packets

Re your question -- it depends: if the network ends up being based on Yggdrasil, as the blog post suggests it could, "IP addresses" are public keys, and packets are encrypted to that destination (which could be a NATing router, though). So, it gives you some guarantees about encryption, that might or might not be redundant (and for some use-cases, better safe than sorry).