Granularity matters. Social feed granularity is small enough that an algorithm, even primitive, can sketch an arbitrary narrative on the spot by juxtaposing unrelated items, akin to a ransom note built from letters cut off from different publications. Pandora and especially GoodReads have large granularity, making it difficult to employ in the same manner.

Very different outcomes I'd say. Are friends and family getting torn apart on those platforms? Do they need armies of moderators to remove abuse material or fact-check posts? (I'm sure there's some, but not on the same scale as Facebook.) This is the first I've ever heard such a thing suggested, and certainly haven't observed it personally.

I was being facetious. GP advocating banning all recommendation engines.

Maybe subject algorithmic feeds to public oversight.

That's like saying a slot machine is regulated by the gambling addict.