Due to Bluetooth simplicity it can be emplemented in a single chip without any support from a coprocessor or network stack. It contains everthing needed. A phyical radio, BaseBand processor, MAC processor, Protocol stack, and stand alone application tasks. It is a SOC (System On Chip) and as such does not need any other CPU/OS/Network stack support.

Try to put a WiFi radio and battery in your ear like you can with bluetooth ear fob.