Brand new, yes, facebook is biased to new stuff. Its just there is a high incentive to repost old shit, because spammers know its effective.

Opposing material? no, that requires comprehensive understanding of the context of the share, the content of the material and the target audience's overton window.

> let users find their own material and/or build their own feeds.

virtually nobody does this, or indeed wants to do it. What's more its very rare that anyone is any good at it (hence why people don't subscribe to news wire services)

also, the research emphatically underscores this. People hunt more, and are less engaged. its more effort.