I think the pdf was quite good, albeit repetitive. In any case, in the end, I think he makes an interesting point about abstraction:
On the surface this seems fairly innocuous; why not make some abbreviations so that
things can be said more economically? The problem is that definitions matter. They come from
aesthetic decisions about what distinctions you as an artist consider important. And they are
problem-generated. To make a definition is to highlight and call attention to a feature or
structural property.
Learning to make good abstraction when programming is a difficult challenge, the right choice can have huge downstream consequences. An educational system which allowed students to get comfortable with the exploration of different abstractions, as well as, the forestalling of notation and rigour until the right rigour was appropriate would be a huge win to reasoning across the board.