I agree. I’d also like to see random beeing part of the std crate, but while it isn’t it is not really feasable to roll your own there for any project that isn’t yet another random.

I wouldn't. If there was a "Writing Python in the real world" document, that's where it belongs–but the official documentation should only really use things that come with Python, with at most a shoutout to good third-party solutions.

So in other words, you want the Rust Cookbook to be dogmatic instead of pragmatic. Which of those would be more useful to beginner and intermediate Rust programmers?

Personally, I think it's a lot more useful to teach beginners and intermediate Rust programmers the extent of the standard library than teach them to grab the first library they find for everything–this is something that they can find out themselves when they realize that the standard library doesn't do what they want. Especially when it's coming from an first-party source like this one.

The point of this book isn't to function neither as the tutorial or intro to the language, nor as a language refererence or stdlib API referenece. It's purpose is to collect common tasks and show idiomatic and practical way to do them in Rust. In the process, its purpose is to introduce central libraries in the ecosystem. It sounds that you want it – and maybe the model of developing software in Rust itself? – to be something entirely different than it actually is.