Whether this area was in fact unusually hospitable to revivalism and social reform movements is now considered to be open to question, but this is beside the point. It was Cross’s methodology and the contours of his argument that struck his readers as innovative and worthy of imitation.
The issue of whether this area was unusually hospitable to revivalism and social reform movements is no longer a topic for discussion, but it's not the key concern. What Cross's readers found significant was his approach and the way he structured his argument, which they saw as innovative and deserving of follow-up.