Those of us who were supporting Windows machines in the ‘00s remember when 100% of Windows machines not behind NAT were pwned in minutes, while those with NAT were fine indefinitely. Should a firewall have been doing that job? Yes. Were firewalls doing that job, in practice? No, NAT did, and it was very, very effective.

I have… concerns about removing NAT from everyone’s house now that IOT is a thing. Could it be done safely? Yes. Will it? Signs point to no.