Very good explanation. It’s an often overlooked property of NixOS and why I often feel like Nix on other systems is an okay way to get packages but you’re missing out on all the good stuff you get through the modules, like losing 95% of what makes the concept good.
I don’t think NixOS is the best possible solution to the problem, but it’s the only original distribution that even tries to tackle it instead of just working around it.