So here's the thing. My ISP does _not_ rotate my IPv4 address, but _does_ rotate IPv6. Why? I'll never know.
Anyhow. I'm not confused about NAT vs. firewalling. No one who dislikes IPv6 is confused by this.
"No one"; LOL. I've participated in entire sub-threads on HN with people insisting that NAT = security. I've cited well-regarded network educators/commentators and vendors:
* https://blog.ipspace.net/2011/12/is-nat-security-feature/
* https://www.f5.com/resources/white-papers/the-myth-of-networ...
It also explicitly acknowledges that NAT has side effects that resemble security mechanisms.
In typical deployments, those side effects mean internal hosts are not directly addressable from the public internet unless a mapping already exists. That reduces externally reachable attack surface.
So, the disagreement here is mostly semantic. NAT is not a security control in the design sense, but it does have security-relevant effects in practice.
I personally do consider NAT as part of a security strategy. It's sometimes nice to have.
The biggest security-relevant effects of NAT are negative. It makes people think they're protected when they aren't, and when used with port forwarding rules it reduces the search space needed to find accessible servers.
I agree it can be a useful tool in your toolbox sometimes, but a security tool it is not.