>> a stateful packet filter works just as well without NAT
True, but NAT doesn't work without statefully filtering/routing packets, and unlike generic packet filters, the use of NAT is basically a requirement for most people connecting devices to the internet.
The question is: if IPV6 was around 30 years ago and no one ever needed to use NAT to stick a whole address space behind a single address, how would things be different today? How long would it have taken for packet filters to become a default feature on home routers, and what would their default settings be?
Routing isn't stateful at all, and NAT doesn't need a stateful filter, it just needs connection tracking (which is also needed for a stateful filter, if you have one).
How common are stateful packet filters on home routers today? I don't really know - thanks to NAT, you can get away without for most attack scenarios nowadays, so I wouldn't be surprised if vendors don't really bother with it. But given that connection tracking doesn't seem to be that difficult with home router hardware, I would have expected stateful packet filters in home routers as a default feature early on, with everything inbound blocked by default (and then some UPnP like protocol for opening ports as needed, just without the stupid address collisions you get with NAT).
True, but NAT doesn't work without statefully filtering/routing packets, and unlike generic packet filters, the use of NAT is basically a requirement for most people connecting devices to the internet.
The question is: if IPV6 was around 30 years ago and no one ever needed to use NAT to stick a whole address space behind a single address, how would things be different today? How long would it have taken for packet filters to become a default feature on home routers, and what would their default settings be?