What does Pariser mean when he says we've moved from human gatekeepers to algorithmic gatekeepers on controlling the flow of information? Why is this a problem?

i think it's the first one because doctors aren't the ones who get rid of the old needles. most of them time it's not even doctors who give you shots, it's nurses.

alzheimer's disease is a brain disease where you forget things that happened moments, even seconds before hand. reward me plz