I like Nix but I think the current model of reinventing a new set of declarative configuration settings for each package is fundamentally misguided and will not

I like Nix but I think the current model of reinventing a new set of declarative configuration settings for each package is fundamentally misguided and will not scale in the long term (look at the number of program-specific options in Home Manager for example). The nice thing about container-based systems is that all the existing documentation for configuring a given program continues to apply as expected. Of course the tricky part is figuring out how to compose them together.