Your solution applies to people who want to tinker for the sake of tinkering. Not to the people/engineers who want to get stuff done, easily and efficiently.
For Arch, I would agree. Things break in mysterious ways and you may spend days tinkering to get a stable system. NixOS is entirely different. Once you get it working how you want, its set and forget. There are tons of simple set ups like this out there, often relying on some combo of WM + "Desktop shell" (noctalia, caelestia, etc) or simply using a fully baked DE. Using something like that cuts out the tinkering and lets you start on whatever work you are doing right away.
Aparently DHH has been looking towards NixOS and have been talking with people. Lets see if there Omarchy base will change...