I don't doubt that what you're describing is real, I'm just skeptical that this is unique or has much to do with Facebook, advertisement or "the algorithm tm" in particular.

Thirty years ago your mom would likely be listening to talk radio, if that's the kind of media diet she's looking for. There's lots of deep reasons why people consume what they consume, I just think it's wrong to attribute a lot of agency to these platforms.

It's actually comforting to think that twitter, FB etc are destroying discourse when in reality it's people on the sites, out of their own volition, or through (lack of) education, socialization, etc.