Because an "email, a cloud account, and a face scan" are not Bitcoin keys. The keys still need to exist. How are the keys stored in these three places? Do you think someone's email account password is more secure than a cryptographic key? Most people use the same email & cloud storage, and a picture of someone's face can pass a face scan. Not possible that it is more secure than keeping the keys yourself, especially if you do a multi-key (or split-key) approach and keep the keys in different physical locations.