When you say that people are doing a "poor job managing their subscription feeds and such", it almost sounds like you think that's possible using Facebook's interface?
At a minimum, you could unfollow people/pages that were too low signal:noise to be worthwhile, and mute the ones that you wanted to follow but not here from. Crude, but easy way to ditch a lot of the noise.
But people didn't really use those basic tools. They just followed... everything... didn't mute the annoying family they were obliged to friend, and complained when their feed sucked.
It's hard for me to imagine Facebook et. al. providing useful controls that people will actually use that doesn't reduce down to "give us some signal and our AI will magically figure out the right thing". And basically that's the extreme version of what they have now.