Well I guess it depends how deep you're in the rabbit hole already, I think it's relatively easy for me at this point to create a new package (I'm maintainer already for quite a few). But yeah ... steep learning curve ... Less so with Nix itself, though non-the-less, it's a simple functional programming language with a new paradigm (derivations). But rather NixOS/nixpkgs Nix magic. For example there's a dynamic dependently typed type-system built on top of untyped Nix in the NixOS module system that is spin up on evaluation time.

But I understand your point, at the beginning of my NixOS journey I have also rather created a "good enough" Dockerfile. Depending on the exact context I still do this nowadays (often because there's an official well maintained docker image in comparison to a not so well maintained Nix one, and the context is too complex to maintain/develop/extend it myself). But if there's a good solution in Nix I rather use that, and that is often less headache than setting up a service with e.g. docker-compose. I also use flakes mostly for a dev environment, if you're a little bit deeper in it, you can spin up a relatively clean dev env in short time (I'm often copy pasting the ones I have written from different projects, and change the packages/dependencies).