[gaganyaan]

Nix has been around since 2003, NixOS just takes that to its logical conclusion. cloud-init may have been inspired by it (I don't know), but certainly not the other way around.

By snarled mess of state, I don't just mean the way it works on first install, I mean the bundle of mud that imperatively managing a system inevitably turns into, with bits of this and that config left behind.

Try playing around with a few different window managers to feel the pain. NixOS makes it easy to try out new config and revert to the old config without muss or fuss.