NAT enables dogshit endpoint security, yes, but that's the problem. Without NAT as a crutch, endpoint firewalls and service security wouldn't suck. Compared to other feats of security engineering the industry has undertaken in order to make centralized cloud services happen, namely JavaScript and the ability to safely run untrusted code from the nastiest corners of the internet at high performance, this would be downright trivial. It just never happened because we had NAT.