To be clear, I was not trying to say his points were void of validity. I was trying to append some clarity to properly differentiating between a developers general knowledge base, a developers temporary knowledge base, and the actual day-to-day doings of the developer. They are not equivalent sets of things even if they intersect.

As a personal anecdote, I know I have learned many things on a project that really helped improve the code, that today I am not able to recall and would have to go back and re-learn with a minimum of a refresher. This happens a lot too. :)