> basically acting as stateful firewalls Stateful Firewalls are the security tool. NATs being mediocre to somewhat alright stateful firewalls "out-of-the-box"

> basically acting as stateful firewalls Stateful Firewalls are the security tool. NATs being mediocre to somewhat alright stateful firewalls "out-of-the-box" before adding a real Firewall is the accident (and sometimes bug). Something doing security by accident (or as a bug) isn't a security tool (just like security through obscurity isn't a security tool). You can have Stateful Firewalls without NAT. Everyone saying that you "need" NAT to have Stateful Firewalls doesn't understand Firewalls or even possibly why "firewall" is and has always been a different word from "NAT". NAT has something to do with security, but that's being generally always paired with a good firewall, not being a mediocre firewall mostly by accident.