“The vast majority of people using NixOS do not understand the language, and simply copy/paste example configurations, which mostly works until you need to do something complicated, at which point you’re completely high and dry.”
No global installs, every package in its own hashed directory, and as many versions side by side as you like. That part is right, and every distro should steal it. The language that drives it is hard to learn and badly documented. A handful of experts maintain the plumbing for a long tail of people pasting configs they don’t understand.