>other than port forwarding

>other

Well you just handwaved away the most significant difference between NAT and native IP, obviously there won't be any major difference to discuss about anymore!

No, we can't ignore port forwarding. The key thing to realize about NAT is that someone owns the NAT. Back then, the NAT lived inside each of the home routers, so even if you have a "strict" NAT (endpoint-dependent mapping NAT, i.e. one that doesn't allow for hole-punching), you can easily bypass it by setting up a manual port forwarding entry.

With CGNAT that's no longer possible, you do not control the NAT. If your ISP decides to screw you over, you essentially do not have a choice but to get a relay, which needlessly costs you money.

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But if you really want to know what advantages native IP has over NAT, I'd say the lack of keepalive packets (to keep a holepunched NAT entry from being removed) is a pretty nice thing.

"What's the difference other than the difference?". Not being able to forward ports means I can't play Tricky Towers with my friend (who isn't technical enough to join a VPN with me and would have privacy concerns about doing so).

> What's the difference, other than port forwarding? Does NAT cause some sort of unique issue that makes existence miserable?

The difference is that your home router does not get a public IP on its WAN interface, but perhaps the non-publicly-routable 100.64.0.0/10 [1] with CG-NAT.

So if you don't have a public IP address, how exactly are you supposed to forward anything? What is the other end supposed to connect to as an IP address?

[1] https://en.wikipedia.org/wiki/IPv4_shared_address_space

Hole punching, which has various forms, may or may not work. This means if you're doing something realtime, you may need to stick a server(reachable endpoint) in between it, at the very least reducing performance.

It makes everything slower and more expensive.