Remember Auratones? Aka Horror Tones? They were very popular with engineers in the old days to see how a recording will sound in a worst case scenario. I'm pretty sure these were not used to evaluate levels of musicianship OR recording quality. There would be maybe a couple of different monitors on the meter bridge for that The large monitors are for the clients and the final mastering stage uses a system to assess the final sound prior to mass production and again samples of the mass produce media prior to release. Again these professionals do their work on whatever is handed to them. It's their jobs. No cherry picking of performances.