We've taken 90s LAN architectures and applied it to cloud infrastructure. Why do I have a VPC? A NAT? IPv6 solves that. "Security" but AWS EC2 security groups

We've taken 90s LAN architectures and applied it to cloud infrastructure. Why do I have a VPC? A NAT? IPv6 solves that. "Security" but AWS EC2 security groups predate AWS VPCs.