I'm still annoyed that most bluetooth headphones haven't figured out how to provide stereo sound at the same time as using the microphone. There is definitely enough bandwidth in bluetooth 5
This changes with LE Audio (spec released in March iirc) which is much more channel oriented (e.g. 2 channels stereo playback + 2 more stereo microphone), has a new codec (LC3) and has support in the upcoming android release
In fact for voice and streaming apps that aren’t classified as telco apps it doesn’t even switch.
The Bluetooth 5 spec is over a thousand pages long.
The Lite Edition spec is "only" a few hundred, IIRC.
You may remember the switch from bluetooth connections being something you had to manually enable every time you wanted it, to devices just being connected all the time (without causing your battery to drop). That’s what LE enabled.
The switch to the single packet network approach obviously also simplified everything else you might want to transmit.
The audio specs are still from the pre-LE era with different modes for everything you might do (modem, fax, headset, headphones, HID, etc), and LE Audio introduces a new and clean way for that.
LE Audio is built around a channel concept, where a channel is unidirectional and a connection can have multiple, e.g. listening on 2 stereo channels and when a call arrives enabling 2 mic channels in the other direction for stereo microphones
Don't go around throwing shade at the spec authority if you haven't read the spec
On Linux, it used to work quite okayish with pulseaudio, even automatic switching between profiles, when an application requested microphone. Since pipewire came around, much higher quality.
As for "reduced", as in, worse than simply monoplex stereo headphones (no headset/microphone support), true, but it's a bandwidth-related limitation, not software impmentation limit, AFAIK