I've wondered about this for podcasts too. I noticed a scary habit where I would play podcasts when I was feeling lonely. Over time, you feel like you're pals with the hosts and something about the audio format checks the social needs box in your brain, thinking that you're hanging out with another human. I don't want to unconsciously sate my social needs with podcasts so I've been more intentional about my listening.
As for people growing attached to the persona, here's an interesting case: https://youtu.be/VJJ90qpzark?t=458