Someone, perhaps at Apple: Please explain this behavior.

I turn on my Bluetooth headphones. I watch a video on my Mac. The video ends. I turn off the headphones. Some other device, perhaps a phone or iPad, elsewhere in the room immediately starts playing music through its speakers using the Music app. I did not ask for this. I do not want this. I think this is an inexplicable design choice. I just turned the headphones off; why is that a signal I want to listen to something somewhere, anywhere that you can find? Baffling.