yeah I know you did not ask!
Have you noticed that people talk about social media, especially Facebook, in terms of drug addiction? Anything thought about in those terms cannot be good in the long run. The question then becomes the same as for any agent that modifies our body or mind. Is the good it does more than the harm/side effects? No answers just the question.
drug addictions almost always destroy lives. Facebook just gives us license to indulge ourselves foolishly, selfishly, but also to communicate in good ways.