That's why jazz theory is valuable, sometimes people don't want to spend decades re-learning things that other people have already learned. Also, I'm just plai

That's why jazz theory is valuable, sometimes people don't want to spend decades re-learning things that other people have already learned. Also, I'm just plain not as good a musician as, say, Duke Ellington was, and there's a benefit to being able to understand what he was doing so I can try to imitate that style and incorporate his techniques into my own playing -- I don't want to rediscover all of his lessons completely on my own because I'm not talented enough to do that; very few people are.