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.
Based on research, a significant majority of podcast listeners—up to 94%—multitask while tuning in, with about 59% doing so regularly. Podcasts are often chosen because they allow listeners to consume content while their hands and body are occupied with other tasks.
But even 6% to 41% of the market is still alot.