Anything is possible with sockets… and that is a meaningless statement. It is like saying you can build anything with bricks. Technically true, but missing all the important details of how.
In an alternative universe we could have done so many things differently to solve the same problems. But we don’t live there and in our universe dbus was the attempt to solve that problem among others. And yes you can create a standardization for music players easily enough - but what about notifications, and everything else? DBus tries to be a generic interface anything can talk over at a logical level - rather that just being the basic way two process can physically send bytes between each other.