I think so many platforms these days employ so many attention-grabbing techniques, that they wear down people. So now they have to go to the bottom of the barrel, notifying you for things that aren't really notifications -- the fact that you haven't posted in a week, for example.
The content quality is abysmal. People simply do not care to share on Facebook in ways that they have in the past. Their awful algorithm ruined the user value.
I think if they returned to a default chronological sorted news feed, with still sprinkling in ads as they do, they could increase the amount of time people spend on the service, show more ads, and increase revenue all while providing a superior experience. Why they don't return to this level of simplicity that the platform once had is beyond me. Too many engineers and too many PM's pushing for their pet projects, I assume, and you really just end up with an overdeveloped product.