Interesting to see the documentation emphasized here. I don't use Arch, but I often see the arch wiki in google results for linux stuff I look up. Makes me wonder why wikis aren't used more for documentation.
Other distros have wikis but tend to focus more on documentation the distro specific details. Since Arch packages have very minimal modifications from upstream, this means much of the content from the ArchWiki is applicable across distros. But then once you have one wiki covering the generic advice, there's less motivation for others to duplicate that effort anyway.
Wikis take a lot of maintenance by a determined core of contributors, or else the pages deteriorate into a pile of incoherent edits. Occasionally I see this even on the Arch wiki. Main text says “do this.” That’s followed by some text saying “I tried this and it didn’t work.” That’s followed by a text box saying “that method is deprecated.”
True, but where docs have a dedicated, core maintenance crew, they can maintain the docs in a good state with less effort. With a wiki, the problem is that drive-by editors can degrade a good product, requiring constant work by the core contributors to revert bad edits.
My main point was as a response to the original question, which was: why aren’t more docs in wiki form? I think one reason for that is that good docs require dedicated contributors, and I think a wiki does little to nothing to reduce their burden.
The myth of the wiki is that by erecting it, drive-by contributors will build a great product. I don’t think any quality wiki was built that way.
I'm a deb-based user but I constantly refer to the Arch wiki to understand best practices and solve problems. No other distro has this level of self-serve documentation that's actually updated and easy to understand.