What you've written is good, but it isn't what the FAQ is for. The FAQ exists to host as short as possible answers and/or links to lengthier content hosted elsewhere.

If you feel the existing answer can be improved without making it longer, I'd merge that. And if you host a longer writeup elsewhere and feel we should link to it, adding that link would be a mergeable change.

But as it stands, this isn't a direction I want the FAQ to take.

(Part of the problem is that a lot of the material you've added doesn't address questions that are actually frequently asked. The fact that topic X is frequently asked about doesn't mean that the best answer is something that goes into every nuance about X.)

One further thought: I acknowledge that it's perhaps sad or not ideal that there is such an unfilled gulf between the brief, just-the-basics style of documentation in the language tour and the very complete and technical style and not especially learner-friendly style used in the language specification. But even if that gap could or should be filled somehow, it isn't the FAQ's place to do it.

(cc @bishabosha and @sjrd , since this is good context to have for anyone who might be reviewing FAQ changes)

There might be a SO entry, but "why doesn't map(_) mean map(x => x)" is a FAQ. Maybe it should be a FAQ with an answer but no explanation. Not sure if there is currently an explanation short of the spec.

Or instead of adding to the FAQ, we could start a section, "QOTOA" questions one tires of answering.

Worth adding that the original "One-Question FAQ" was a thorough explanation.

Oh, the current FAQ found a clever solution to accommodate it: