Is Nix harder to learn for somebody who knows nothing about computers and OSes? Probably not. It might even be easier.
But that's not Nix's primary audience. It's targeted at people who already know a fair bit about the current paradigm and have plenty of skill with it. For those people, it's very different. Things that are easy for them will be hard until they learn the new paradigm.
I get that people who have already learned Nix and like it are in the new paradigm. Understanding it is not a problem for them. But pretending that work doesn't exist for others is unhelpful. And this sort of casual dismissal makes me suspect that even if I learned Nix, the experience still might be pretty bad. If Nix advocates can't take seriously the difficult noob experience, maybe the experience is painful all the way through.
You have never asked the same detail of questions for any other os who can’t even provide grantees the answers won’t change next update, or when you install some random package.
Don’t pretend like you needed to know the user and mutability of directories when you have had a user for your printer dawmon and systemd and not once did this stop you from using a distro.