Do you think you would be able to produce a song while somebody else was watching? Not interfering in any way, simply watching, silently judging your every move. :)
I probably could but I wouldn't do a very good job.
Having a creepy voyeur at the back of the room would feel weird. It's either a collaboration or GTFO.
It works a bit like what is known in physics as the 'Observer Effect'. Merely observing the process fundamentally affects the outcome.
When I work I need to feel completely uninhibited. Talking aloud, arguing with myself, telling my internal heckler to shut the fuck up. Sometimes I have to work naked. If you saw me in the studio you'd think I was a bit mental.
I wouldn't even want my wife to witness that.