Both podcasts and blogs are difficult to monetize. But does that have to be the point of a podcast/blog? I'd say no.

Plenty of people write blogs for themselves and for learning/teaching. Why not do the same thing for podcasts? Those who are truly invested in the medium and want to provide value to others (and themselves) will do it long enough to make it successful. I mean if you try a podcast for 6 episodes and quit...sorry, you probably were never going to be successful as a podcast owner.