Earlier quoted context omitted.
The issue such devices have in practice is upfront cost, compatibility, the need for port forwarding, and the lack of redundancy so you don't lose your data. Among other problems but these come to mind. Centralization solves those problems because you can connect to a server instead of port forwarding, your data might be stored across 3 servers, the cloud storage might be as cheap as free, and applications are design…
IPv6 will help by eliminating NAT (and thus port forwarding problems). IPFS might help with redundancy. But yeah the cost and complexity are major problems. I think the biggest problem is making open standards that can evolve quickly. All the big chat platforms have switched to proprietary protocols so they can iterate and roll out changes on their own.
Which NAT/PAT/port-forwarding issues are you thinking of?