So how would a newcomer go about getting gigs and becoming known, if so many festival organizers won't take a chance on someone new? Sometimes it seems like its always the same old same old on the festival circuit, I guess that's because organizers already know who they want to book and won't consider anybody else?

I agree that it's very frustrating to get no reply whatsoever - especially in the case of an e-mail where it's so easy to just type "sorry we already have our lineup" and hit reply.