If a burglar steals it, you can run at the bank to take your 'backup list of passwords' and start changing your passwords.

If you lose it, same thing.

Then you re-create another book so that there's always one in a safe at the bank ; )

I've got a list of all my passwords, without any encryption, in a safe at the bank. They serve two purposes: in case I forget my passwords (I do write them down at home in some 'encrypted' form that is not meant to resist the NSA but that would stop 99.99999% of all the burglars on earth) or in case I die (my family would then be able to access my various online accounts).