> extending the lifetime of IPv4 by 20 years and providing isolation between internal and external networks are not inherently bad.
It's hard to see how things would be worse in the alternative history without NAT. IPv6 deployment would have come much sooner - it's been ready for so long even in our current timeline.
Ambiguous addresses (RFC1918) aren't good for isolation, firewalls are. It's a common security problem that people end up joining different RFC1918 networks, and then don't know what the ACLs mean anymore. Isolation is provided by firewalls, not NATs after all. A NAT's job is to try to proxy traffic back and forth, not block it.
> extending the lifetime of IPv4 by 20 years and providing isolation between internal and external networks are not inherently bad.
It's hard to see how things would be worse in the alternative history without NAT. IPv6 deployment would have come much sooner - it's been ready for so long even in our current timeline.
Ambiguous addresses (RFC1918) aren't good for isolation, firewalls are. It's a common security problem that people end up joining different RFC1918 networks, and then don't know what the ACLs mean anymore. Isolation is provided by firewalls, not NATs after all. A NAT's job is to try to proxy traffic back and forth, not block it.