Everything – buying clothes, conducting financial transactions, and communicating with our friends and colleagues is conducted through our devices.
Today, nearly all of these actions require the user to sign into a website. The device is nothing more than a dumb terminal or conduit between the user and the cloud. This is a missed opportunity, as our devices are vastly more qualified to assert credentials and are generally ascribed significant personal protection by their owners.
If you accept that most of your communications with the internet happen through the same device, you would benefit by having that device assert your credentials. Using your phone is less of a hassle, reduces errors during login and provides significant account protection because possession of your physical device replaces or augments the use of username/passwords.