I have seldom found personal notes from far in the past to be useful. If there's something worth noting down, then it goes into documentation, so others can stumble upon whatever quirk I've come across in the future. If there's something I really want to remember, I create flashcards and do spaced repetition until I've learned the thing. But that's just me, and I imagine my way doesn't work for a lot of people.
I think people are taking this post a little too personally and literally. This is a writer's piece. The title is meant to share a philosophy that this developer subscribes to. Nothing about it is declaring that others must subscribe to it as well.
If a pen and notebook don't work for you, then don't use it.