No, not everyone runs behind a NAT system. Ever been to a university where everyone gets an non-RFC1918 IPv4 address? That&#x27;s how IPv6 is. When I worked at Microsoft, everyone had a routed address on their workstations, too.<p>As you just admitted, NAT breaks things. Double NAT and CGN breaks a lot more. What about people who have no choice or no say in whether or not their Internet is NAT&#x27;d? There are ISP&#x27;s where customers don&#x27;t get routed IPv4 addresses. They get RFC1918 addresses and lots of double NAT&#x27;ing occurs. It&#x27;s a bad scene.