> I can’t think of any common requirement that will be afforded to users having devices that will never need to be publicly reachable be publicly addressable.

Because you do not know ahead of time which devices may have such a need, and by allowing for the possibility you open up more flexibility.

> [Residential customers] don't care about engineering, but they sure do create support tickets about broken P2P applications, such as Xbox/PS gaming applications, broken VoIP in gaming lobbies, failure of SIP client to punch through etc. All these problems don't exist on native routed (and static) IPv6.

> In order for P2P to work as close as possible to routed IPv6 in NATted IPv4, we had to deploy a bunch of workarounds such as EIM-NAT to allow TCP/UDP P2P punching to work both ways, we had to allow hairpinning on the CGNAT device to allow intra-CGNAT traffic to work between to CGNAT clients, as TURN can only detect the public-facing IP:Port, hairpinning allow 100.64.0.0/10 clients to talk to each other over the CGNATted public IP:Port.

* https://blog.ipspace.net/2025/03/response-end-to-end-connect...

By having (a) a public address, and (b) a CPE that supports PCP/IGD hole punching, you eliminate a whole swath of infrastructure (ICE/TURN/etc) and kludges.

When it was first released, Skype was peer-to-peer, but because of NAT "super nodes" had to be invented in their architecture so that the clients/peers could have someone to 'bounce' off of to connect. But because of the prevalence of NAT, central servers are now the norm.

A lot of folks on HN complain about centralization and concentration on the Internet, but how can it be otherwise when folks push back against technologies that would allow more peer-to-peer architectures?