A refinement on your point: music does not exist independent of sound. A musician is responsible for creating that sound, whether the expressiveness of the instrument is great or limited. A mistake (IMO) I hear a lot is a musician playing an electronic keyboard as if it was a piano, ignoring the fact that the sound they are generating is bad, simply because they are actually ignoring the sound. Just pushing the keys down as if they were playing a piano. For an keyboard the instrument is the control interface, sound generator, amplifier, and resonating body (speaker). Anything that makes sound can be used to make wonderful music, if there is a true listening process.