I agree that there is a place for both styles in the world. Unfortunately when it comes to rust most of the tutorial seem to be in this style, and I thought at least the "advanced" guide would be more "sensible". I enjoyed Learn You a Haskell, but that was an introductory text. If I am reading an "advanced" text on a systems programming language I probably expect it to be a little more formal.

>In regards to sounding childish, I find that in general to be an unusual criticism. Perhaps there are people who speak this way as adults simply because that is who they are?

First off, maybe it wasn't the best word for me to use. However, the second statement is a tautology; of course if they are childish then that is "who they are": childish people. The term to me doesn't denote an interest in "childish" things, like the CS Lewis quotation seems to say. Rather it denotes "not fully emotionally developed" which is usually a judgement placed on their current behaviour. You can read all the fairy tale books you like, I don't care. But if you start exhibiting the negative behaviours typical of children - selfishness, irresponsibility, etc - then yes, you are a bad person and deserve to be called out for it. (I'm not suggesting this at all about the author - this is now a separate discussion.)