BSD ties the kernel and the software on top of it together pretty heavily, creating the expectation that the documentation should cover all of it.
Linux is meanwhile kernel and software kept separated, meaning that the documentation usually winds up assembled from separate tools, each with their own standards.
* Extremely short documentation. Everyone has seen these, a tool where the man page exists but provides almost no actual information.
* Unfriendly reference-type documentation. GNU programs are often guilty of this, coreutils certainly comes to mind. On the upside, it's usually comprehensive. But it's not good - it's a short description followed by a sequential list of every option, so the functionality is described in detail but there are no usage examples, no list of the most common options, or anything like that. Great reference, poor usage documentation.
* Too much info about ancient systems or historical details. Yes, it's great that many of these utilities are portable and can run on different systems or work with files from different systems. The man pages for zip/unzip mention MS-DOS, Minix and Atari systems, while defining the zip format as "commonly found on MS-DOS systems". The man page for less explains that it's a program "similar to more(1)" - completely useless info now - and mentions that it has some support for hardcopy terminals, again information that's not important enough for the first paragraph in 2025.
* Poor keywords in the description. There's the theoretically useful apropos command. My Xorg wouldn't start so I tried to remember how to start my wifi up. apropos 'wlan|wi-fi|wifi|wireless' doesn't mention nmcli, which I was thinking of, though it does at least provide the much more difficult iw command.
* Technical project-specific jargon that makes it easy to find the solution - if you already know it, that is. For example, Xorg documentation generally doesn't use the word "resolution". It's not in the xrandr or Xserver man page, and in the xorg.conf page it's only a reference to virtual screens. Because X uses the term screen size. That's fine, understandable and even accurate but most people would first search for 'resolution'.
A shared or central wiki sounds nice, but could quickly end up too messy. Arch having its own makes sense, as in the case of Linux - the distro is the operating system. Arch is a different OS from Fedora, which is a different OS from Ubuntu, etc. Sure, there's a lot of overlap but they are each their own unique OS.
Practically speaking ArchWiki has everything I'm likely to need as a poweruser, but it's not really all that comprehensive.
An interesting but gargantuan project would be a Linux distro that maintains patches for all of its packages that standardize directory structures, config file locations, CLI argument order, etc.
<https://web.archive.org/web/20081023145740/http://www.gentoo...>
And when it came back online in november,
> Gentoo-Wiki recently had it's database lost; this is the rewrite of the site
<https://web.archive.org/web/20081204053828/http://en.gentoo-...>
The arch wiki describes the upstream package.
I say this because Arch tries to use the upstream software as-is, and describes requirements and helps make configuration choices.
Other distributions tend to make the choices for you, configuring and modifying upstream to fit the distribution.
With respect to a wiki, this would be another layer of documentation to add. Describe the package, describe the distro, and explain the configuration choices.
I haven't even used Arch on any of my machines but can't count how many times I've found their wiki useful for my workstations, servers and even custom Yocto-built systems. Arch supports many ways of doing a thing, so whatever tool I'm dealing with, Arch probably supports that and documents it on the wiki. And Arch makes few changes from upstream so the wiki instructions are often applicable on any distro. Sure, it takes some familiarity to recognize when something is e.g. Debian-specific and should be done in a Debian way, but as a user fairly familiar with Linux, I often find Arch to be the best source of documentation.