NAT and CGNAT break the basic idea of how the Internet was designed, forcing everyone into servers and consumers. We've just become used to it, and most people have never experienced it any other way.
The Internet was supposed to be a purely peer-to-peer network, where the addresses on each side of a connection pointed to an end node. That's why protocols like FTP or SIP break when NAT is used, and why you have to play games with port forwarding if you want to run services from your house (assuming you have a public IP address at all).
The Internet was supposed to be a purely peer-to-peer network, where the addresses on each side of a connection pointed to an end node. That's why protocols like FTP or SIP break when NAT is used, and why you have to play games with port forwarding if you want to run services from your house (assuming you have a public IP address at all).