I would say that while some 'source' singers made a living by busking (Margaret Barry & Davie Stewart spring to mind), most of them had only limited performance opportunities, their full repertoire only discovered by collectors seeking out songs.

Some sang at home, with or without their family but many only sang at social events, where there were other singers (like a modern singing circle) and two or three songs might be the nightly limit.

Maybe it's the concept of the folk club guest night which is where we went wrong- I'm sure Fred Jordan didn't do voice exercises, he didn't need to but he never had to do 2 x 45 mins several times a week until he was discovered- are professional folk singers attempting the impossible & we should go back to the old ways?