I think it is important to note that the music that was played by middle and lower class amateurs in the early part of the 20th century (and earlier) was more l

I think it is important to note that the music that was played by middle and lower class amateurs in the early part of the 20th century (and earlier) was more like This Land Is Your Land than anything as technically difficult as the Goldberg Variations. Group singing (and dancing) was an important component, and mistakes were not really that important. I spent a bunch of time talking to my Dad who learned to play under those conditions. It is a real difference from the generations that have quality recording by technically proficient musicians easily available.