Well, microstates come before probabilities. They are just there, while probabilities are in the model that describes macrostates (emergence). This is similar to how one calculates entropy with the Boltzmann equation, assigning microstates to (emergent) macrostates, S= k ln W. But yes, there is no known argument that would derive the Born rule from just counting microstates. Anything like that would be a major breakthrough.
Well, microstates come before probabilities. They are just there, while probabilities are in the model that describes macrostates (emergence). This is similar to how one calculates entropy with the Boltzmann equation, assigning microstates to (emergent) macrostates, S= k ln W. But yes, there is no known argument that would derive the Born rule from just counting microstates. Anything like that would be a major breakthrough.