What about dedicated Bluetooth headsets for phones, like plantronics? Aren't they supposed to work bidirectional with high quality audio? Or do they also use the standard Bluetooth profiles/protocols?
Bluetooth headsets like the ones Plantronics make are designed for making phone calls, and the limitations of the standard Bluetooth headset protocol weren't a problem for that because standard phone lines were monoaural with the exact same frequency response and bit depth limits so you weren't losing anything extra. The trouble is that people want to use Bluetooth audio for things like gaming, video conferencing, using voice assistants whilst playing music etc which have much higher quality audio. Also, phone calls themselves are slowly improving too with things like HD Voice.