The notion is that by making logins dependent on a physical device, users will benefit from both ease and security. Without a password, there is no need to remember login information across services or risk compromising security by reusing the same password in various places. Similarly, because signing in requires access to a physical device, a passwordless system makes it much more difficult for hackers to compromise login details remotely; and, theoretically, phishing attacks in which users are directed to a fake website for password capture will be much more difficult to mount.
