Manjaro has no purpose, it's half-assed at being arch and it's half-assed at being stable.

My experience with Manjaro and Fedora, OpenSUSE etc. contradicts yours. Manjaro has the best balance between stability and rolling out of the box I've seen.

"Out of the box" is key here. You can tweak any distro into doing anything you want, given enough time and effort. Manjaro achieves a good balance without the user having to do anything. I remind you that I've tested this with non-experienced users and they have no problem using it without any admin skills (or any admin access).

Debian testing is a rolling.

It is not.

AUR isn't a problem in Manjaro because of lack of support, it's a problem because packages there are made with Arch and 99.999% of its derivatives in mind, aka latest packages not one week old still-broken packages.

And yet I've managed to install dozens of AUR packages just fine. How do you explain that?

Matter of fact, I've never run into an AUR package I couldn't install on Manjaro. What package is giving you trouble?

Manjaro literally accidentally DDoSes the AUR every now and then because again they're incompetent.

You're being confused.

AUR had very little bandwidth to begin with and could not cope with the rise in popularity of Arch-based distros. That's a problem that needs to be solved by the AUR repo first and foremost. Manjaro did what they could when the problem became apparent and has added caching wherever it could. Both Manjaro and Arch devs have worked together to improve this.