I sometimes listen to podcasts, close to none of them were discovered inside a podcast app, and the one that were, it was because an author of a podcast I was already listening started a separate one. I used to think that podcast had a discoveribility issue, but I'm honestly not that sure anymore. I don't usually get new books/ebooks suggested by my phone either, and after all, a podcast and an ebook have more things in common than different from each other. I trust word of mouth over algorithm to give me good reading suggestion, and off course I do the same with ebook (in the more sporadic occasion when I want to use ears rather than eyes), maybe it's just unreasonable to expect podcast to act differently.