What you say is sound but, IMO, not complete. There's something more to immutability vs. mutability. They both can, for instance, describe both data bases and m

What you say is sound but, IMO, not complete. There's something more to immutability vs. mutability. They both can, for instance, describe both data bases and mathematics. But there's no doubt in my mind that mutable state is better suited for the former, and immutability for the latter. It's "stuff" vs. "knowledge" that's modelled; stuff wants to change and knowledge wants to be shared.