Exactly. "Things I own alone" are no good as passwords, if they cannot be changed. They are account identifiers only.

And if a password has sufficient entropy (not likely to ever be duplicated) then the account identifier is pointless. Just use the password as sufficient authentication.

personally i do change my birthday and mother's maiden name for every service i sign up for.

i make up random answers and write them down in the notes of my password manager. i always try and recommend others do the same.