Comment by drnick1
The issue is that we DO NOT want every device to have a publicly routable IP address. It does make sense for some machines, but you probably don't want your your Internet-of-Shit devices to have public IPs. Of course you can firewall the devices, but you are always one misconfiguration or bug away from exposing devices that should not be exposed, when a local network is a more natural solution for what is supposed to remain local in the first place.
- NAT is not a firewall. A firewall is a firewall. - NAT is not better than a firewall. - NAT does not replace a firewall.