Did you actually bother to read the post? The post specifically explains the headaches associated with Apple sign in. In particular - "Another issue is Sign in

Did you actually bother to read the post? The post specifically explains the headaches associated with Apple sign in. In particular - "Another issue is Sign in with Apple’s “Hide My Email” feature. With this feature, if you create an account with us, Apple will generate a special email address just for that account. So rather than your email address being john.doe@icloud.com, we will see your email address as something like dpdcnf87nu@privaterelay.appleid.com. While this is an intriguing idea that provides a measure of privacy, in practice it creates numerous support and user experience headaches..."