How is that different from a discussion forum?

Also, I think it's pretty normal to listen to podcasts when you're actively engaged in another activity like driving or cooking, and that's probably a big reason behind their popularity. You can't do that with a text-based chat, unless there's someone to read the text to you...in which case I think everyone would choose to hear it in the speakers' original voices.

You have chats like in WhatsApp, then you share these chats like Youtube videos. People then read & comment on these chats.