Of course, writing down passwords is such a bad practice. But there's no way I can afford to burn the cycles to memorize 13 new passwords every 90 days, so I use the same password for all work systems. The same bad password.
Nothing inherently wrong with writing down passwords. You move from "something you know" to something you have, As long as you properly secure "what you have", it's still decent single-factor authentication. Just write your passwords on a $100 bill, and you're fine.