Comment by bux93

This is one of those occasions where people are arguing semantics, and you're like "but -- I was there!"

My first cable modem did not have a NAT, nor did my first ADSL modem. You'd use "Internet Connection Sharing" on Windows 98 SE to share the internet connection on your LAN. And you'd get badly hacked, and then also install a firewall. Sygate had a firewall and NAT combined. (Or, you'd use linux - and also get badly hacked, but for different reasons.)

As a response, ISPs started to ship modems with built-in NATs. They did not start to ship what we now call routers (modem+NAT) because they wanted to encourage people to share their internet connections out of the goodness of their hearts. They'd prefer to sell more cablemodems, or dial-up. They started shipping (NATted!) routers because it saved them a lot of support calls from hacked (and disconnected) customers. Instead they got support calls about port-forwarding, so uPnP was the next hot feature.

Was NAT originally intended to be a firewall? No. Did it effectively protect many innocents? It did. Is it still needed as an additional layer of security-through-side-effects? Let's hope not.