This is a misconception holding back the adoption of IPv6. Routers have a stateful firewall meaning by default they only allow incoming packets that belong to

This is a misconception holding back the adoption of IPv6. Routers have a stateful firewall meaning by default they only allow incoming packets that belong to a connection that was initiated from the inside. By default you also have this kind of firewall on every operating system. NAT adds 0 additional security.