I admit AUR was a huge reason why I made the move to Arch. But with Flatpak gaining more and more traction, the benefits of AUR are shrinking fast.

The setup is kind of a kind of a logical fallacy here. More people are using Debian and RPM based distributions than Arch Linux. That being said:

Arch Linux has the AUR because at the time it was developed, the standards for distributing software on Linux were either RPM or DEB repositories. AUR was a necessity because one could get software on those distributions from the official vendor, but nobody was supporting Arch Linux. So it was a stopgap, an equalizer for one outlier platform.

It's hardly the first such repository: FreeBSD ports and NetBSD pkgsrc predate the AUR by over a decade. Slackpkg predates AUR by a couple of years as well, though possibly not slapt-get. Gentoo has portage. Anyway, they took an idea that was already well-established, and catered it to a distribution that had fewer software options than major distributions.

These days it's still the same scenario: a placeholder, to equalize what's available for Arch Linux users versus other distributions.

People use Arch because it is a rolling release with a well-documented wiki. AUR is a nice perk, but hardly the main reason that people are using Arch Linux, given that other similar systems have existed for older distributions and operating systems for longer.

The majority of other distros value package managers that allow for complex graph evaluation of dependencies, and the ability to roll back. This is granted with rpm and Deb, but not for pkgsource, which is a pretty lightweight format compared to those.

As for AUR, the major distros (Ubuntu, Debian, Fedora) support 3p repositories as well. The main concern is security. IIRC one of major complaints for AUR in the past was that it didn't foresee a strongly secure distribution system.

openSUSE has OBS, Fedora has COPR, and I'm pretty sure both Gentoo and NixOS have similar stuff. Do Ubuntu's PPAs count? Flatpaks and AppImages are also similar, although they are more limited and they aren't exactly "standard" packages.

when it’s the main reason why so many people use Arch Linux?

AUR is one reason why I use Arch. But not the reason. Besides AUR, Arch has many other advantages from my point of view. Like for example the wiki that also users of other distributions use. Or the many vanilla packages. Or that you can easily create your own packages through the PKGBUILD files. Or that, based on my own experience, Arch is quite problem-free to use despite the current packages.

One reason why other distributions don't have something like AUR could be that AUR is not an official offering, so no verification is done in advance either. Thus, it has happened at least once that someone has manipulated PKGBUILD files in bad faith (https://lists.archlinux.org/pipermail/aur-general/2018-July/034151.html). The Wiki does not warn against the use for nothing.

However, it is much easier for the user to check the files in the AUR in advance than it is, for example, with ready-made packages in an unofficial PPA.

With https://build.opensuse.org and https://mpr.makedeb.org there are also at least two offers that are somewhat similar to AUR.

NixOS has NUR, but it's not necessary because they take everyone's pull requests in the official repo. I've been maintaining the software I use myself on the official nixpkgs, so I don't need to use the NUR.

Fedora has COPR, Opensuse has the OBS (which also works for other distros), NixOS (my beloved) has overlays...

Asbestos undies on.

I don't think AUR is a feature, but more of a hazard indicator. If the distributor isn't packaging so many important things that most users have to turn to external services regularly, they're lying down on the job.

I use Arch because pacman sounds cooler than apt, wakka wakka.

AUR is really not that great? Who moves to Arch for it? It's been my main OS for I don't even know how long but AUR has been my primary pain point. PKGBUILD is cool and useful useful. AUR however, is untrusted (or rather shouldn't be trusted), often out of date, sometimes requires compilation, and doesn't even have any good pacman wrappers since yaourt (that I'm aware of).

Am I missing something?

What makes you think there aren't equivalents out there?

Gentoo's Guru repository, for one, and any of the multitude of ebuild repositories available through the eselect repository command.

The AUR is not particularly special.

Don't know. The AUR is a big reason I use Arch. Obviously there's PPAs/OBS or whatever but they're not implemented nearly as well, I don't need to go searching for new repos with the AUR or messing with repo priorities (fun times on Suse...) since everything is in the one place and there's procedures for taking over orphaned packages. I use about twenty or so packages from it, many of them not packaged for any other distro. Personally not interested in using Flatpak since two package management systems is not my idea of KISS. Poor man's AUR imo :).

I'mma let you finish, but Nix had one of the best package managers of all time.

AUR is definitely not the reason people choose arch haha

Fellow Linux folks, this direction is one of the main problems and you know it very darn well.

Because the AUR is a pretty low quality repo. Not sure if anything has changed since 2 years ago, but last I used arch, the AUR was full of broken, abandoned, and unbuildable packages. The Debian repos, fedora+rpmfusion, etc, provide a comparable number of software packages with substantially higher quality, hence no need for the AUR. Fedora actually has COPRs which suffer from the same quality issues as the AUR for similar reasons.

The equivalent for Gentoo is the overlay system. gpo.zugaina.org (which is the best total package index) claims to list over 100000 ebuilds for 56000 different packages (some packages have multiple versions in-tree), and I know their database is not complete, since I contribute occasionally to an overlay that they don't index. Oh, and that also doesn't include things like perl library packages autogenerated by g-cpan.

So, um, yeah, useful but not unique.

For my needs I found that that flatpak just werks for anything not on the distros repos. And for the really obscure stuff I've used, I could just build from source

I think looking at the two major enterprise players (Red Hat and Canonical) can give hints.

Fedora: run by Red Hat, upstream of RHEL. No way they are going to allow an unreviewed repository to be shipped with fedora by default. But they do have guides to add RPM fusion, and copr repos (the closest equivalent)

Ubuntu: run by Canonical. No way they are going to allow an unreviewed repository to be shipped with Ubuntu by default. But they do host and have guides for PPAs (closest AUR equivalent)

Debian: kind of the base layer for a lot of other distros. Debian itself is kept very minimal, and has a whole philosophy on what packages are allowed.

Edit: I realized this implies PPAs, copr and the AUR are the same when I know they aren’t functionally. I am just trying to highlight the motivations behind the distros and how it may play a part

Many distros have independent community generated package repositories though most aren't on official infrastructure. Ubuntu has PPA which is close. I try and avoid AUR as much as I can. It is a potential attack surface and packages are sometimes poorly maintained and break. I like it for system stuff and I mostly review the PKGBUILD. It seems like a good way for software to find a path into the official repos. There was a lot of resistance from me initially but for most desktop applications flatpak has proven to be a better solution.

Arch is special 😁