Serial didn't create the demand for podcasts — that had already existed, as you say — but it proved out that demand, in a way that made advertisers take notice;

Serial didn't create the demand for podcasts — that had already existed, as you say — but it proved out that demand, in a way that made advertisers take notice; made it possible to commercialize podcasting; and so led to an explosion in the number of podcasts, because it was now a predictable media business model that the stodgier kinds of investor could get behind.