I'm firmly a Debian shop, but I find that the Arch Linux wiki often answers non-distro-specific questions that I have about how to do something on Debian.
(Especially since I'm usually using Xmonad without a lot of the "desktop environment" stuff.)
But sometimes it just has the answer you need in an easily digestible format. Top 10 source for me, but not a top 3.
-- Some nerd with almost two decades of distro-hopping experience.
But for getting pointed in the right direction about things that have been obscured by the desktop environments, and then left largely undocumented nowadays, the Arch Linux wiki usually points me in the right direction.
Much of it would be pretty confusing to someone who only wanted high-level documentation in terms of the Gnome Desktop or KDE Plasma, though.
Even as an Arch user, probably at least 80% of my usage of the Arch Wiki is just going through "Troubleshooting" list of previously seen issues and solutions for whatever thing I'm dealing with. I don't go in expecting that everything will work exactly the same for me, but over the years I've ended up with quite a few headaches solved by pasting the right line in the right conf from one of those sections.
Maybe the value comes not just because they bother to maintain a wiki, but that Arch Linux tends to select for above-average technical people, even more than Linux in general does. (Even if Arch people strangely don't run Debian goodness; but we benefit from a diversity of perspectives, even if they are unexplained. :)
I briefly used Manjaro, Debian and Ubuntu before that, and now am primarily a NixOS user, yet I still find myself coming back to the wiki.