The threat model is always important. What does your home look like? Who are you protecting from? If your current home is a shared student accommodation, post-its are probably a bad idea. If you live with potentially abusive family members, it may be a bad idea.
But in many cases when you don't live your life online and login everywhere with your Google account federation - sure write it on a post-it. It's not good enough though if you have 20+ accounts and would make you share a password between them.
Your very right. It’s all about threat models. I would rather my grandma (or really anyone that would have a hard time dealing with a password manager) have a password journal then all her passwords be the exact same thing.
But in many cases when you don't live your life online and login everywhere with your Google account federation - sure write it on a post-it. It's not good enough though if you have 20+ accounts and would make you share a password between them.