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.

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.