Very interesting paper, thanks for posting it.
I don't entirely agree; along with Charley, I would give more credit to the development of the music hall and minstrel traditions- a combination of English and American roots and American proliferation of this popular type of entertainment, based on Black-influenced rhythms especially those of the work songs of the ports (you have presented this well).

Which raises a question- why did not the agrarians and port workers of Europe and UK develop work songs to go along with their labors?
(To put the question in harmony with chanties nomenclature, why 'forecastle' and recreational songs only?).