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 AUR however, is untrusted (or rather shouldn't be trusted), often out of date, sometimes requires compilation, and doesn't even have any good pacman wrappers since yaourt (that I'm aware of).
It is technically possible to install paru through Cargo which you can get just from pacman by installing rust and you can install pikaur through PIP. Both can mess with your systems packages though so I do not recommend it.
AUR however, is untrusted (or rather shouldn’t be trusted), often out of date
So basically like a PPA which are used by many users of Ubuntu. The only difference is that the PKBUILD files used to build the packages are easier to check than the final packages in a PPA. And that's exactly what is a big advantage for me.
sometimes requires compilation,
This is often because a project does not offer ready-made packages that can be downloaded from Github, for example. There are also people who do not trust ready-made packages from unknown third parties. I wouldn't necessarily download and execute a binary file from a Dropbox of a user I don't know. Compiling is the safer way if the source code is downloaded from a more trustworthy source.
and doesn’t even have any good pacman wrappers since yaourt (that I’m aware of).
Personally, I don't think aurutils, paru and yay are bad. I currently use aurutils myself. But as far as AUR helpers are concerned, everyone has their own preferences. That's why there are so many ;-)
Yeah, AUR isn't great because it's engineered as a second class citizen given the necessity of third-party tools like yaourt, and that the whole process of installation can't be done directly through the first-party tool (pacman), such that updating the main packages can trivially cause third-party packages to suddenly stop working. ArchLinux offers just one way - their way - when it comes to dealing with software versions and if the user happens to depend on some thing they want to keep around, tough luck, and hope that future upgrades don't force a breakage that requires a recompilation which may no longer work.
That runs completely opposite to Gentoo, where the first-party repositories are defined the exact same way as third-party repositories, and that updates to first-party libraries generally don't immediately break existing binaries because the distribution was built with recompilation requirements from upgrade breakages in mind. Since third-party packages are treated no differently (no second class citizen treatment), their first-party tool (emerge) can manage the complete lifecycle of "third-party" packages in the exact same manner (as opposed to needing any third party tools to manage the build). This alone reduces the mental bandwidth for the end-users that are managing their set of required packages for their systems. All this flexibility is ultimately part of the various reasons that got me to switch from Arch back to Gentoo.