Taking into account they had to take extra steps to enable this "feature", they probably don't consider it to be "misconfigured", at least from their point of view.

A NAT is going to have to have a timeout, otherwise it will gradually leak and run out of ports. All protocols that operate behind NAT must implement keepalive.

The solution is IPv6. Then you don't need your ISP to maintain a stateful connection table.

I'll be pedantic: you mean that the solution is no NAT, with IPv6 being something needed to get there. Nothing stops you from NAT'ing IPv6.

> Nothing stops you from NAT'ing IPv6.

Nothing stops you from filling your car with orange juice either.

NAT'ing IPv6 works and is merely not a necessity. It could still have a purpose, It just won't be address exhaustion.

Filling your car with orange juice presumably stops it from working and is likely to cause damage, all while your parents question where things went wrong.

As proven by Microsoft in Azure's IPv6 support.

The solution is IPv6.

There is no such thing as a properly configured NAT implementation that does not have timeouts for idle sessions. Without those you’d run out of memory on your router and new sessions would be blocked.

NAT is fundamentally not the solution.