This ignores... a lot of reality. Like the fact that when IP was designed, the idea of every individual network device having to run its own firewall was impractical performance-wise, and decades later... still not really ideal.

There's definitely some benefits to glean from a zero trust model, but putting a moat around your network still helps a lot and NAT is probably the best accidental security feature to ever exist. Half the cybersecurity problems we have are because the cloud model has normalized routing sensitive behavior out to the open Internet instead of private networks.

My middleboxes will happily be configured to continue to block any traffic that refuses to obey them. (QUIC and ECH inclusive.)