[omgJustTest]

It means it is not by default, which as we know, is a powerful choice these days.

ie enterprise customers will enable it, consumers will do it if they are tech savvy and your mom/dad/granddaughter/grandson/nephew/niece will have the default option.

when you are at home you will have nat and when you are not you will be uniquely identified.

[Dagger2]

If you can be uniquely identified without NAT then you can be uniquely identified with it too, because IPs don't contain your identity. You get them from a combination of the network prefix and a random number generator.

There's generally no reason to be enabling NAT when you have enough address space to not need it. It can be a useful tool in your toolbox sometimes, but it's not something to be enabling by default.