Folk music was always the style of music that most focused on lyrical content.....words....therefore it tends to attract people who are strong in their literacy skills. It also tends to attract people who are interested in knowing about past history in detail. It's just natural that people who are drawn to folk music would also tend to be the types who would go into teaching.

Most other styles of music are more about "the groove". They're more physical, in other words. Or they're primarily about emotion/sexual attraction ("love songs"). The style of music that appeals most directly to thinking about and focusing on the meaning of the song is folk music.

It is a teacher's job to think, to focus on meaning, and to impart that to others. (at least it should be, anyway...)