I get where you're coming here, maybe the concepts in the book weren't difficult for you, but they were for me. I tried Rust without the book and got disillusioned so quickly as I didn't have the vocabulary to understand the docs or a lot of discussion (stack overflow etc) i bought the book and it openened up so much understanding for me and now I have a couple of Rust projects on the go.

I guess it upset me a bit because I didn't find Rust fun at all until I had the book and I could see how your piece could discourage people from buying it.