So what you're saying is that because people accidentally end up hearing the same things over and over and that sways their opinion, we should on purpose make them hear the same thing over and over so we sway their opinion the way we want? There couldn't possibly be any downside of that, could there?

Wouldn't it make more sense, upon noticing, "Gosh, these people keep getting bad information," to say, "Hey, what they need is more information"? Maybe fewer echo chambers, recommendations based on topic but not point of view?

(Some types of content may legitimately be psychologically damaging, just like some types of physical contact--it's reasonable to take appropriate precautions in the face of documented psychological harm from mere exposure.)