How long ago was your experience? That might be a factor. I have been using Arch for a long time, and if my memory serves, stability was a bigger issue years ago than it is now. These days, I have found Arch to be really solid.
However, I come from a business perspective here. You really don't need an operating system that introduces new versions on a whim in the middle of operations. There's a reason businesses run RHEL/Centos or macOS and whatever has LTS in Windows land: cost of maintenance and reliably wide windows of no possible breakage.
As a business, it's kind of a dodgy position to be at relying on "yeah, randomly upgrading versions worked for me so far. Fingers crossed, lol".
So I'm interested in what people use their Arch Linux for and what didn't work for them on any other stable platform. My personal observations point towards the Arch Linux users being the tinkerers who like to use cutting edge and hose their Debians trying to wedge some newer version into it. While the ones that ran screaming away from Arch pretty much never had the desire to change the underlying system and were happy with a security backport now and then.
You don't want your PHP version to endlessly get updated during your operation when you build your app at a specific version.
It would mean not only you have to take care of distro update gotchas but you have to go through all the breaking changes the language introduces.
Stick with LTS. Rolling is for enthusiasts, though Arch does have put decent efforts on their wiki but I did find errors on minor pages that didn't make it work as written.
I think we'll figure out how to upgrade in the 2-3 years of support PHP has for each version. Trying to compare this to arch's rolling release style is bananas.