Why are binary objects so critical to astronomy?

Question

There are a lot of astronomical objects out there to study but binary objects seem to get more attention. Why is this? What makes binary objects (stars, Kuiper Belt Objects, black holes, galaxies, etc.) more important or special than lone objects?

Answer 1

Because they interact with other stuff.

A black hole without an object to interact with is meaningless. White dwarfs cannot go supernova 1-A without being in a binary (or greater) pairing. "Gravity waves" (which I am not fully sold on) have not been detected without a binary pair of collapsed star cores combining.

List goes on.