I notice people tend to argue about X when it's actually a proxy argument for Y, but they don't know themselves that it's Y.

Y is a legitimate concern or fear, but X may not be. But everyone wastes each other's time arguing about X.

If you figure out Y, you find common ground and compromise and that's when you find solutions.

In my experience the Y is often the even more profound disagreement between two people, and explicit discussion of Y could be enough to obliterate a relationship completely.