Nowadays, everyone is forced to remember lots of sensitive data to interact with machines during daily life. For instance, automatic teller machines ask for numerical passwords, and email accounts are protected by using loginnames and passwords.
For many good reasons passwords should be difficult to guess and every password should be used for one account only. In reality, this makes it quite difficult for the average person to remember all the different passwords.
Hence, people tend to choose easy-to-remember passwords and many people re-use their passwords in such a way that the same password is used for many accounts. Even worse, it is quite common to write down passwords and stick the note to a screen frame. All these facilitations of remembrance lower the burden for hackers to get access to sensitive data and abuse computers.
The idea behind Safe is that a user must not remember all their loginnames and passwords. Instead, the user utilizes their cell phone to store sensitive data in an encrypted way. Only one root password is required to be remembered to get access to the data.