I'm surprised the article makes no mention of Adam Carola's podcast. Possibly due to some of the controversial remarks made by Carola on the show https://en.wikipedia.org/wiki/The_Adam_Carolla_Show_%28podca.... I'm not a fan, but if you're mentioning Serial and WTF, Carola's podcast is right up there as far as numbers go, and was involved early on in monetising his podcast with adverts etc.