At least there is an interesting aspect to this idea: Usually the singer is always regarded as much more important than the "accompaniment" by the audience, as generally people who don't play an instrument are rarely aware of how important harmony (and rhythm) is in music as opposed to melody. So this would somehow "turn the tables" and put the harmonic part into the focus. But of course I'm pessimistic the audience would accept it, as the playback aspect would be much more obvious than if a keyboarder in the background was playing midi files instead of playing live.