> You just asserted that without explanation.

They linked a whole article detailing the complexities of specifically NAT traversal.

I should think it obvious that by removing an entire leaky layer of abstraction the process would be much simpler. Yes, you still need a coordination server, but instead of having to deduce the incoming/outgoing port mappings you can just share the "external IP" of each client--which in the IPV6 case isn't "external," it's just "the IP".