Hey, glad you raised this. It's true that not all content works narrated. We offer an editing service to make content ready for narration & break it up into manageable episodes.
Yes, we work with real narrators who really care about delivering the best possible reading. TTS is fine but it's never going be able to engage an audience in the same way a real voice can.
We wanted to optimise for human engagement so we went to real people :) TTS is fine for some things but very few people actually want to listen to a robot reading to them.