What are reasons to not use flake utils?

[voydus]

fwiw, I’m starting to feel like genAttrs might be enough?

outputs =
  let systems = [ "x86_64-linux" "aarch64-darwin"];
  in {
    packages = genAttrs systems (system: {
      default = nixpkgs.legacyPackages.${system}.cowsay;
    });
};