I was thinking more of a guy mixing with either headphones or 2 monitors and trying to put the audience in the back ground.
Very dependant on method of recording/mics. used.

In that aspect I would expect most recordings of them becoming a backup singer. By default almost. Plus the recording artist probably never heard an Omnidirectional Active Loudspeaker, let alone even knowing it now exists.
The blueray concerts could be quite entertaining with the audience as more backup vocals