that's a bit simplistic imo. software doesn't matter, sure; what matters is what the software lets you *do*. but "interoperability" is not a goal in itself. it's a means to an end. for different software that let you do fundamentally different things in fundamentally different worldviews, there can be no meaningful interoperability.
example: fedi has concepts and abstractions for "posts" and "profiles". what happens when you don't have these same building blocks?