Not really. It's the user's fault. Apple provides an option to hide your email, it's not required. It's an option that shows up when you're prompted to create an account.

Oh, I agree with this.

My original thinking was that Apple makes it too easy for a general audience to hide their email without considering the implications (the service won't know your email). But of course there's a tension here, since you also want the option to be easy and accessible.

The party I do not consider at fault in this case is Anthropic.