I disagree with your response. When I have my bluetooth headset connected to the iPhone and NOT playing music, when I get a text message it beeps in my headset to tell me I got a message and then starts playing music.
There was NO music playing at the time. This is not just about the bluetooth standard for connecting a device, because my device was already connected.
There may be a bluetooth standard, but this is being caused by interactions with how audio (from more than the music app) is being handled on the iPhone and should be something that can be disabled. The iPhone is currently setup to assume that if you have a bluetooth device connected to the phone that you want to play with music. Given this is a multimedia device, handling phone calls and video calls and audio from multiple sources, it's a bit odd that they would assume that all you want to do with a bluetooth headset is listen to THEIR music app.
What is needed would NOT violate the Bluetooth standard, and yes we know it's not a feature of the iPhone, that's why tens of thousands of people are complaining about it.
Telling people to "go buy something else" (sure I'll throw a $1,000 phone in the garbage because of this) and "stop whining" is inappropriate. This is a forum about that very topic, and by the way, if you don't like this topic, and don't have anything positive to add, why are you on this topic commenting?
Otherwise I will need to DELETE the Apple Music app, and just use Spotify. Is that what Apple wants?