How Useful is a Production of Culture Perspective in Understanding the Birth of Rock and Roll?

When was rock and roll born? Some would say the 1940's, when Wyonie Harris's 'Good Rockin' tonight' (1947) was released and others like Rolling Stones Magazine, suggests that the first rock and roll single was Elvis Presley's 'That's All Right'' in 1954. 

Richard A. Peterson described rock and roll using six key terms that he believed influenced its rise in 1955. He concentrated on the social context and how it affected rock music, rejecting the view that the emergence of certain artists such as Elvis and Chick Berry in the 50's; were responsible for rock and roll. He explains that new technology, such as the television and the use of the transistor helped to broaden the rock audience. Peterson's theory overlooked one main factor; he does not address the music itself. In 1955 circumstances came together but he doesn't explain why the music that emerged was rock and roll. Why was it not the breakthrough of Jazz music? I believe that Peterson's theory is too general as it sets up a framework that could refer to any type of music.