Actually, the author is assuming that you will generate a password like `Password123!` for an obviously fly-by-night company and use a password manager for other websites of medium trust, the author states as much. My reading of his suggestion is that the memorized passwords are used for things like ssh or possibly logins on laptops/pcs. Some people have a good instinct for such things.

This is quite reasonable.

- Useless passwords for useless websites that needlessly require accounts. - Autogenerated passwords for websites of infrequent use that you don't need to trust much. - Memorized passwords for logins of high importance that you need to trust.

Since we only have so much capacity to memorize a password, the idea of reusing a password for the few high importance logins you have can be quite reasonable.