As joshstrange mentions above, iCloud password prompts don't support password managers, which is the main reason why I have a memorable one.

Password managers are more useful to me than a spreadsheet in iCloud. I don't see why having a memorable iCloud password implies I should get rid of a password manager.

Do you have a spreadsheet of passwords in a cloud account somewhere?

A password manager mitigates other threats that a spreadsheet in iCloud Drive does not, such as a program just directly reading it and ruining your life. And, anyways, password managers give you auto fill which is a significant quality of life improvement.

A memorable password is not a bad password, if done right. I have a password for both my google account and Apple ID that's easy to type because when you're in device setup you can't auto fill and so random passwords are a huge pain

Password managers plus biometric auth mean I almost never even need to copy-paste a password, let alone type one. I just hit "fill" and it fills it in. For most of the services I use these days, I've never typed or manually pasted the password, ever, not even once.