The shepherd can afford to sing for hours because he has a job herding sheep. The modern musician, by contrast, is often told to "get a real job" so they can afford to make art (fortunately, I followed this advice twenty years ago and now only make music as a hobby). Your argument also implies that the "purest" form of music is one generated by people who have no choice but to work in the fields; it suggests that if musicians want to find "pleasure" in their art again, they should perhaps accept poverty and obscurity as the price of admission; ironically, that's the reality of a majority of musicians today.