It's a perennial problem; if your passwords are secure, you have to write them down (in a text file, etc.), and then you lose much of that security.
Let's take a hypothetical example. You used to use the password "password". Your favorite website forces you to implement various "rules" to make it more secure.
YOU MUST USE A CAPITAL LETTER
Password
YOU MUST USE AT LEAST ONE NUMBER
Passw0rd
YOU MUST USE AT LEAST ONE SPECIAL CHARACTER
Pa$$w0rd
YOUR PASSWORD MUST BE AT LEAST 9 CHARACTERS
Pa$$w0rd!
See how you follow all the rules, but still end up with a pretty crappy password?
You can't beat human nature. People always find away around embracing the SPIRIT of various rules. "Malicious compliance" and such.
No meat on Friday? I'll have an Impossible Burger (or seasoned, deep fried catfish that basically tastes as good as fried chicken).
No snacking between meals, but liquids are OK? I'll just drink a milkshake between meals.
Humans are so good at doing this.