I used Arch for years, and left it due to poor stability. Every time I would try to use an AUR app it would be broken and need re-installing. Sure the non-AUR stuff was mostly fine, but a lot of necessary applictions are in AUR, and AUR is touted as a major selling point of Arch. When there was an issue during a system update, recovering the system was a mess. I also cannot call it stable when you can't update one application without updating the rest of the system.

I switched to Gentoo and it fixed all the issues I was encountering with Arch, and was more stable. Now I'm on NixOS, which is far more stable than Arch or Gentoo were.

Now, that said, the way SteamOS uses it, I don't see any issues. With an immutable system, A/B updates, and tested images, the compatibility and update issues are solved. Using flatpak for user applications solves the rest of the noted issues. Would be ideal if I could install with Nix instead of Flatpak, but ran into some trouble there.