The Emacs documentation really is quite good. It is user–centric, as you say, starting by naming the things the user can see and interact with when they run Emacs (the menu bar, the tool bar, etc, etc) before going on to more complex topics, such as how commands are given via the keyboard or mouse.

While it is detailed, it can hardly be called overloaded. The real reference material is in a completely different book, the Emacs Lisp Reference Manual. There is also a FAQ, and if you’ve never programmed in Lisp before then there is the Emacs Lisp Intro. Then there are something like 60 other manuals for various packages that come with Emacs, like Org Mode or the calculator. These all serve to keep the core manual from becoming overloaded with details.

You can read them all online at <https://www.gnu.org/software/emacs/manual/>, should you care to try to prove me wrong.

I estimate that about 30% of questions on the Emacs StackExchange can be answered by quoting from that core manual, another 20% by the FAQ, 20% by the Elisp Intro, the Reference, or the docstrings of individual commands, and another 10% by the manual for Org Mode. The calculator comes up occasionally too. Perhaps 10–20% of the questions on the site are actually interesting questions that require real thought or a look at the source code.