This is not the internet I've been sold in my youth, and this statement makes me sad and angry.
Your MAC and/or IP address should not identify you, and never should have been used as an identifier. It's the identity of a communication endpoint.
If the OSI model is about making the core of the network stupid and fast, which has proven benefits of scalability and/or extensibility, then identity/authentication is not the network layer's job and never was.
If a protocol assumes all hosts on a subnet are trustworthy (ARP/DHCP for example), it's an upper-level protocol design failure, not really having to do with transport (TCP/UDP)/network (IP) layers.
There is also SCTP.
I literally don't see a single thing to be sad about. Angry is even a little harder and honestly a little surprising.
You want VOIP, sorry your double nat'ed connection messes up about half the time, you better by telephone service with us instead.
E.g. if everybody uses IPv6 China can still block you when you are located in their network. Not a single grain more power to you.
You still can, and you really don't have to host with a big provider if you don't want to. The only reason we hear about it so much is because all the engineering articles come from people who work at companies with insanely high scaling requirements. If you want to throw up an XAMPP server at home you still can, though you'll need to acquire either a static IP or a dynamic DNS record to point people to.
That's the whole point. With some ISPs using CG-NAT, you don't have a public IP.
I have three computers at home running an SSH server. Two have to be on non-default ports, since I only have one IP.