Aren't "data" and "program state" mostly one and the same? Encapsulation can easily be seen to matter whenever one has several plausible representations of data

Aren't "data" and "program state" mostly one and the same? Encapsulation can easily be seen to matter whenever one has several plausible representations of data/state that all are to some extent isomorphic to each other, and one wishes to operate on these representations in a way that can be easily verified to respect the isomorphism, and not to rely on irrelevant details. These considerations are actually becoming more relevant to FP rather than less, especially as we're slowly gaining a broader understanding of the potential of newly-developed features such as homotopy types, in enabling one to write programs that can work directly with such isomorphisms, ensure that desirable encapsulation-like properties hold, and even convert code to work "across" any arbitrary change in internal representation.