The thing is, the security elements of those things are often only marginal and were not the purpose of their existence (in most cases), and they mostly (though

The thing is, the security elements of those things are often only marginal and were not the purpose of their existence (in most cases), and they mostly (though not all) boil down to security-through-obscurity. We're all mostly agreed that security-through-obscurity generally only provides a false sense of security and isn't the real deal. So, what if instead of working around an IP limit with all this complicated technology, the same folks had instead been working on good point-to-point encryption for everything all this time? And, what if all that complexity didn't have to exist in every device? Every line of code increases the likelihood of a security bug, and a network stack with all this extra stuff has a lot of extra lines of code. I dunno if NAT code has been responsible for exploits, but I'd be shocked if it hasn't. NAT didn't come into common use for security purposes. It just didn't. It came into common use because not every company owns a big enough sub-network for every device to have an IP and no individual household does. It would require completely rewriting history to suggest NAT is and has been used primarily as a security feature. Certainly, VPNs have a useful purpose other than dealing with the IP shortage of IPv4, but a lot of VPNs at the corporate level are used to tie two private networks together. And, a lot of development has gone into that purpose. I'm just saying that in a world without a strictly limited set of IPs over the past decade or two, we would likely have a very different looking internet, and I think it'd be a better internet than what we have, because of how much effort has gone into dealing with the complexity of NATted/tunneled/VPNed/etc. networks.