The problem is after the tutorial is done, all the libraries (look (like (this))) and the language is so powerful it is difficult to know if this 10kb contains a life-changing insight into the nature of programming or a half-hearted implementation of half of something that was a bad idea to start with. Knowing the syntax and technical semantics of the language doesn't help with that.
The topic has been done to death, but the lisps seem to have a social organisation problem that the community never quite managed to get a grip on.