Right. Say you forget your password. Say you get to a customer support agent and they tell you how to get a password reset sent to your alternate email or phone number.
"Um, I don't have an alternate email and my phone number changed when I moved countries last year."
They'll probably (and correctly) maybe make sympathetic noises but basically say too bad. Presumably this wouldn't happen with a (non-trivial) company where there's some level of known identity. But for an individual there would presumably need to be a last-resort process that required real-world identity verification in some form.
"Um, I don't have an alternate email and my phone number changed when I moved countries last year."
They'll probably (and correctly) maybe make sympathetic noises but basically say too bad. Presumably this wouldn't happen with a (non-trivial) company where there's some level of known identity. But for an individual there would presumably need to be a last-resort process that required real-world identity verification in some form.