Mutable state does not necessarily mean OOP. For instance, in Clojure I could write a multimethod that updates refs of type Student, and Course: (defmetho

Mutable state does not necessarily mean OOP. For instance, in Clojure I could write a multimethod that updates refs of type Student, and Course: (defmethod assign [Student Course] [student course] (alter student update-in [:courses] conj course) (alter course update-in [:students] conj student)) There is polymorphism and mutability here, but we're not dealing with objects. So to rephrase my question: what are the advantages of OOP when dealing with mutable state?