> I mean, what's the big advantage of Docker and the whole "container" movement? You are guaranteed (more or less) to have a known state. Why does resetting hardware fix problems? Because it resets things to a known state. Managing state is the problem, and functional paradigms are the solution.

I would argue that, with Docker, you may or may not have a known state. You certainly have a fixed state, but whether or not the state is "known" depends on how you generated it. If you use something like Nix (or Guix) to create the image, then you have a chance of knowing the state and being able to understand it. But if you build the image in some other way, there's a good chance that you won't be able to understand the relationships between the components, and that you won't be able to change the relationships safely and effectively later on.