From Mark Zuckerberg's 15th-anniversary post; also see Has Facebook been good for the world? | Vox
"We've made real progress on these issues and built some of the most advanced systems in the world to address them, but there's a lot more to do. We're now taking steps that wouldn't have been possible even just a few years ago -- for example, this year we plan to spend more on safety and security than our whole revenue at the time of our IPO, and the artificial intelligence required to help manage content at scale didn't exist until recently. But as people use these networks to shape society, it's critical we continue making progress on these questions.Mark Zuckerberg on Facebook at 15
At the same time, there is another force at play as well. As networks of people replace traditional hierarchies and reshape many institutions in our society -- from government to business to media to communities and more -- there is a tendency of some people to lament this change, to overly emphasize the negative, and in some cases to go so far as saying the shift to empowering people in the ways the internet and these networks do is mostly harmful to society and democracy."