The difference between "has a routable IP" and "this should be routed" is exactly the problem for 99% of the population.
I'm not saying NAT is a good thing but at least it's one more thing from preventing network shares of everyone's pictures on shodan. I'm also not saying it's a good protection, but it's not zero.
Maybe if ipv6 had been the default since the beginning, then OSes and default configs would have been written in a better way.
Oh! This is how the Internet was supposed to be!
Remember, we only even bother with NAT bullshit in the first place because there aren't enough IPv4 addresses.