It's a tool right, and from a usability, stability, security, and functionality perspective its second to none. No other program (for me) works more seamlessly between desktop and mobile.
It's messaging app is first class. Tons of features. I can type a message on a pc, and carry my phone with me and pick up where I left off.
It's groups allow people to self organize, at a scale I dont see anywhere else.
It's newsfeed is what you make of it. If you follow your friends you get what your friends share. If you follow ars technica, foreign policy, indewire, mit, open culture, priceonomics, saveur, you get ars technica, foreign policy, indewire, mit, open culture, priceonomics, saveur. Theres really no one to blame but yourself and the people you follow if your newsfeed sucks, or isnt what you want it to be. Follow better people. Fake news, tribalism, viral videos as the new opiate/soma of the masses, speaks to human nature and what we have become, not the tool that lets us mindlessly consume and push away our problems.
It's gmail, google news, twitter, instagram, youtube, reddit, all rolled into one. For a lot of people who want a stable product that works well, that does those things, it gets the job done. I totally think facebook wields its power irresponsibly at times, but blaming it alone for weakening democracy is like blaming roads for bad drivers.