You seem to be going around in circles, Jim.
First you complain at sharp and co for weeding out the music hall and parlour songs and anything else they may have discarded, then you say these shouldn't be included anyway. You can't have it both ways.

You say we are not social historians. I beg to differ. If you were a social historian you would have no difficulty in spotting the differences between 20th century Ireland and 19th century England.

Of course many of the 'performers' who were recorded compartmentalised their songs. I can also think of many local examples. But I can come up with 20 times as many who weren't 'performers' who didn't, as well. This doesn't prove anything.

The early collectors were absolutely right to be selective. Like us they had limited time and saw the singers dying off. They wanted to get the most useful material recorded in as much quantity as possible. What was the point in collecting the other stuff when it was readily available elsewhere.

You asked me to select a song from the corpus I considered originated as a broadside piece. I did that. I now return the request. From the same corpus a well-known ballad please that you consider did not originate under commercial conditions?