The thing about NixOS is that while using packages are easy, creating them are still really hard and/or undocumented.

With most popular services already being packaged by people who know what they’re doing this isn’t that big of a deal, but when I want to try out something from Joe Schmoe’s GitHub (or worse, something I made myself) it is much easier for me to throw together a “good enough” Dockerfile and compose.yml together in barely a hour of work than to dig into Nixpkgs internals and wrestle with Nix’s syntax.