They're a great source of news. I just activated my Twitter after a decade or so of avoiding it.
Malaysia in particular is vulnerable to propaganda, because political parties own all the major free channels and newspapers. Social media has helped balance it. While the government has blocked Medium, places like Facebook and Twitter bring world news to the masses, including any stories like local corruption that a news site like WSJ would investigate but none of the local ones could.
Also about 80% of my jobs come from Facebook connections, so it is very valuable to me.
If both of those went down, we'd probably move to Reddit, Instagram, LinkedIn, Pinterest. I think those sites are even worse for society.