Much of what those of us in the Sacred Harp shaped note tradition read about shaped notes is related to our own tradition. The following article is apparently by someone in or acquainted with the Christian Harmony tradition.
"Elizabeth Smathers-Shaw, a talented shaped-note singer and daughter of shaped-note master Quay Smathers, explained that many of America's settlers had come with only their necessities. Since music and fine instruments were more of a luxury, the nation, early on, was largely musically illiterate, Shaw said.
"Once things became more settled, organized church and music and education developed. By the mid-18th century, a revolution was under way to teach people music. Many teachers looked for a quick, easy way to do it—a sort of Hooked On Phonics method, Shaw said."
-- From A history of shaped notes, by Michael Beadle [click highlighted portion to link to the rest of the article]