Professional music is called the music that is composed with modern academic technique.
And that means?
Music that implies advanced structural and theoretical considerations and a written musical tradition. Unless I'm not understanding your question?
I understand it quite well I think. Still sounds A LOT like pure elitism to me, established by some people who want to look more professional like others (like the name implies)...
But I don't want to start a flamewar here or anything. We can both stick to our opinions and just go on, dropping the topic.