I don't think blaming employees is the right thing here. These are hard problems to solve, and unless we have evidence that Facebook encourages, or does not try

I don't think blaming employees is the right thing here. These are hard problems to solve, and unless we have evidence that Facebook encourages, or does not try to ban content like this it's probably a strech to call them immoral. We are just beginning to understand the ill effects of social media, and these companies themselves acknowledge it. Plenty of people at these companies are working to solve these problems. What is indeed a wrongdoing of last decade of companies is the growth at all costs mindset which leads to weird engagement hacks (like LinkedIn sending you an email notification for a message but now showing the message content in email), which many times lead them to take decisions that are not at the best interest of consumer. I guess all ad supported VC businesses are bound to have this fate, though.