I get it, you hate Apple. And your blind hatred makes you impervious to learning anything about what is being discussed. Why, what is more fun than stupidly babbling "Apple sux"? It's quite Avant Giarde these days
Of course, there are the more educated folk who look back and say Bluetooth 4.2 specs allowed for subchannels to carry additional audio codec information to allow for better audio sound via Bluetooth; but few if any Bluetooth receiver chip manufacturers supported this standard.
Most didn't know that Apple purchased a silicon development company that specializes in developing ultra low power Bluetooth receivers and made the Apple W1 chip that allows the iPhone to transmit MP3 and AAC files directly to the headset, thus bypassing any Bluetooth audio limitations. The music is decoded in the headset, on the W1 chip, just the channel information that left or right headset needs. What's more, by doing so digitally; Apple can add in equalization and active noise cancelling data- making their W1 equipped headsets noise cancelling by design.
But, hey; that's not nearly as much fun as saying "Apple sux", now is it, Boy Genius?