Writing in the electronic margins

I came across an interesting article about the importance of being able to "write in the margins" and how that functionality has been neglected in computer systems in favor of the designer trying (in vain) to figure it all out ahead of time. I love this quote:

The fuzzy intersection of official and unofficial data has never been a comfort zone for information technologists.

How true...

It also follows a theme that has been recurring lately, which might be summed up as "computer science is hard:" in a sense we are trying to re-create the world from scratch, which is a very difficult job! Paper gives you all sorts of abilities "for free" but every new function on a computer (such as the ability to "write in the margins") must be explicitly designed.