Nixpkgs as a monorepo is great if all you want to do is install FOSS packages on your NixOS linux box. That's probably the biggest use case for nixpkgs, so it's

Nixpkgs as a monorepo is great if all you want to do is install FOSS packages on your NixOS linux box. That's probably the biggest use case for nixpkgs, so it's important, but it's not the only use case. If pythonPackages were broken out into a separate repository (which I'm not advocating, it was just an example), you'd fix a python package by importing the upstream library from the nixpkgs flake, tweaking it locally and then using the local version as buildInput to the python package. Sometimes it would make sense to submit the fix upstream, and sometimes not. At the same time, we really have run into scaling issues—automatically importing all of Stackage into nixpkgs was killing us for a while there. Regardless of whether nixpkgs remains a monorepo or not, I think 2) is actually the most exciting thing about the flakes proposal. Package authors being unable to supply nix packaging within the package repository is a big impediment to the adoption of nix.