They are indispencible in the same way that the blueprints of a nuclear power station are indicpencible and if you are already an expert you may find them even friendly. But if you aren't an expert the docs are cold help becoming one. It's like trying to learn Hungarian by reading a Hungarian grammar written in Hungarian from one Hungarian grammarian to another.I respectfully disagree. In my experience, Unix man pages, in particular zsh documentation, are excellent resources, effectively tailored to their intended audience. I'm part of that demographic and find them incredibly useful.
Difficulty in understanding content, like cooking recipes in my case, often stems from it not being designed for our specific knowledge base. This doesn't diminish the quality of the content itself.
Quality is not in question, rather presumed reader and specific
goals. Again, if you are already an expert the manual is your
reference to recall some detail or other and it could hardly be
better. But if you want to *understand* the shell, best to read
Peter's book or some other resource. The manual stores
information but explains nothing. It is also written in shell
jargon which if fine if you already speak shell jargon.