Password books are basically physical password managers. The only problem I have with them is that the passwords in most password books I've seen aren't very creative or random. As long as you write down randomly generated passwords instead of permutations of the names of your kids/pets/parents, I don't know what people are panicking about.

The perfect password book is combined with a word you remember but don't write down as a pepper, but I doubt it's much of a problem in practice; it takes one leak of an u hashed password to break the code.

I think for many the risk of someone breaking in and stealing your password book is much smaller than the risk of a centralised password manager getting hacked (LastPass and friends).