[tssva]

"Without NAT the only 2 parties that need to know anything about a TCP connection are client and server."

Even without NAT there may be multiple devices between a client and server which need to know about the TCP connection. Stateful firewalls, WAN accelerators, and load balancers are some examples.

[globular-toast]

They should all be under your control, though. Once you hand off to your ISP it should be nothing but routers all the way.

[tssva]

I wish they were all under my control.