For other distros, that kind of behind the scenes changes are triggered by package installation and ad-hoc commands. It's not always easy to figure out exactly what has changed, especially after the fact. This, in turn, makes changes difficult to revert.

NixOS is much better because you can inspect the changes after the fact. You also know which code to look for, which is a luxury. If the code seems too much, there's the repl to help. Changes are also much easier to revert.