Calling NAT the original sin is a serious exaggeration. Carrier Grade NAT (CGNAT) is a truly evil concept that restricts the freedoms of the CGNATed users. But regular NAT is fine as long as you can control it. "No one wanting to bother with port forwarding" is largely a matter of shitty UX on the home gateway side and laziness on the side of the operator. Same with UPnP.
If anything, NAT has saved millions of wildly insecure devices running unpatched old Windows versions from getting pwned the second they connect to the open internet.
If anything, NAT has saved millions of wildly insecure devices running unpatched old Windows versions from getting pwned the second they connect to the open internet.