I would agree that most recommendation engines are as you described. However, my conclusion was that this is a product of people.
Ad revenue increases with time spent on the site. So the goal is to get people to spend more time, if people genuinely wanted to engage with others of differing beliefs, or be show content outside of their obvious interests, then it would make sense to do this in order to increase the magic “engagement” numbers?
So the fact that it’s not happening suggests to me at least that most people are quite happy in their echo chamber?
I’d love to hear your thoughts on this line of semi logic pseudo phycology ;)