Facebook is a great tool for many uses.
The most empowering thing I can personally think of, it lets small organizations/businesses reach a lot of people without spenind any money. Anyone who can't afford a website can still put content out there and reach their audience.
It's great for advertisers. While with AdWords from my experience clicks rarely convert, Facebook works generally well.
Like Whatsapp, Messenger is an awesome free chat that most people will have already installed and that makes communicating with new people extremely easy.
People who complain about Facebook seem to be those who use it improperly, such as not being able to ignore notifications for more than 30 seconds, or sharing private things irresponsibly.