The small performance boost isn't the main reason most people install these distros instead of Arch, they rather have to spend hours reading the Arch wiki and instead want a GUI live boot installer, preconfigured desktop environments that just work with NVIDIA, built-in gaming-meta-packages that make gaming on Linux more bearable.
I just recently made to switch to base Arch from Cachy so I can run Omarchy without any issues and it did take several hours of extra setup just to have a working system but it is nice knowing how to do it now.