The vast majority of passwords does not need to be easy to memorize because they should be stored in a password manager. In fact, I'd argue that the harder it is to memorize, the stronger the password.
Yet they still need to be typed on cell phone keyboards, TVs, or communicated over phone (shared passwords are the best compromise if asymmetric cryptography is not an option), in which case you usually need to spell it out anyway.
Why mention memorizing passwords? Most people have dozens of passwords, and most people would have trouble memorizing even a simple word for dozens of passwords. I have a lot of trouble with those annoying security questions which one would assume would be constant and easy to answer.
Ok, but if there isn't a high-entropy sequence of "something you know" somewhere in the system, you've created some pretty bad failure modes. 1Password requires a master password periodically, but can otherwise be unlocked by AppleID (presumably also true for secure-element biometrics on other platforms).
I maintain that a good secrets management system has a number of passwords which should be memorizable (and memorized) which is greater than zero. Possibly by only one element.
Every password manager I know of, including Apple's, requires a strong password to unlock the vault. FaceID or YubiKey allow me to bypass typing that so often, but anyone trying to get into my accounts or password manager would have to know the strong password and get past the physical/biometric 2FA.
How many more passwords of this format can you construct? `have` is fixed, the `!` at the end is a classic, and the 12 number is pre-determined by true cats and the 3. So the only degrees of freedom you have are:
3CatsHave12Legs!
Easy to memorize, and pretty strong.