This is very true - to fully explain a "hello world" program you'd have to dive into macro syntax... When writing my Rust book I often start by showing the naive solution, and then later move to more canonical code once I've introduced more syntax that enables something more elegant. But I'm aware that I'm showing something non-optimal to start. Maybe that loses some trust, like people think they're learning something only to be told later on that it's wrong? On the other hand if you start with the optimal solution you have to teach so much syntax that it's overwhelming. I expect that some folk want every example to be perfect, but I'm going with an approach where you iterate through each chapter and as you progress through the whole book the examples get better and more idiomatic.
This is basically an eternal battle when teaching. Personally I prefer to try and stay to only idiomatic code if at all possible, but there's pros and cons to each approach.
(This is one reason why I'm glad other people are also writing books! Not everyone likes my style!)
