The thing is, CPUs are designed to execute imperative programs. A stream of instructions is imperative. Until we see real hardware that executes functional programs, FP will always be somehow treated as a second-class citizen in the computing world.
(I'm not sure whether this is a joke, a brilliant idea, or a piece of FP advocacy. You could probably get a CS graduate paper out of trying it, though)
Everything we do is an abstraction.
The Von Neumann architecture is all about state and mutability, and yet FP tries to stay as far as it can from that.
OOP is really a supplement layer over imperative programming and doesn't deny any of its underpinnings.
PS: Computers are not inherently digital, either.
As I understand it, real world FP isn't about "staying away from" state and mutability, its about providing tools for managing state and mutability as a means to manage the complexity of reasoning about programs using it. E.g., Haskell's monadic approach essentially makes every Haskell program one that produces (as the result of the main function) the imperative program that is actually executed by the runtime.