Was reading more on music theory, and apparently BECAUSE Jazz and Blues are both highly improvizational, but also collaborative,
they are fairly rigidly structured. In both, musicians would often play together for the first time at a club, or play with several different bands. The fairly tight structure of the music allows for improvization, knowing that the 'net' or outlined chord structure of the music will allow harmonic re-entry.
Picked up a couple of books, one on what not to do wrong in songwriting, one on melodies.
I wonder if the academic musical theorist of the world relate to the actual songwriters in much the way that the established religious organizations relate to prophets or evangelists. Because working/popular songwriters are willing to put themselves into their music, they are out in the world performing, while as in religious establishments, the well educated subject matter experts of the songwriting world are in the schools (churchs). And also don't have the zeal, fervor or presence of the prophets (performers).
Of course, this ignores the type of successful song writer who is not a performer, who may be much more staid or reticent than the rock bands who cover his songs, and more closely resemble the music theory academics.