If harm means physical harm, maybe -- or maybe not: apparently many people definitely thinks that facebook live is a popularity contest and start streaming their suicide on it [OP, and Google - 0]. Here, to understand why fb might be the reason people did that in the first place, you should ask if live streaming functionality is all that people wanted, then why streaming suicide attempts on youtube wasn't a (or, as big of a) problem?
But I think on a more intricate level, harm also means slowly sinking, and being depressed, then to me, Facebook is a drug that does exactly that.
There are studies which concluded that people are actually happier without fb [1]. Personally, I found that to be true: I feel depressed browsing the meaningless statuses of people bragging about trivial things or sharing political news. I find fb isn't even a platform that I can share "what's on my mind" (like it always prompts) anymore. Everything is tied to my real name with no other option. I can't share the stories at work because co-workers on facebook will see. I can't share anything about my relationship because our mutual friends will see, and my girlfriend gets pissed off. I can't share my good news because people will think I am a dick who want to brag. I can't share my bad news because people will get worried more than me. I can't share hobbies because my friends don't have the same hobby and they don't care, so no reaction, so I get depressed because no one cares.
So all I can share is shitty vacation pictures with me smiling like an idiot, and inconsequential news. Those are the news that pleases everyone: The lowest denominator of me and everyone on fb. Fuck that. Also, I found out that my behavior on fb is extremely similar to an addiction behavior. That includes finding it not useful but keep coming back, repeatedly checking it for new stuff, coming back after deactivating.
I used to think Facebook messenger was essential. Not until I found myself not reading the messages and don't care what people say in 1000s of groups I am in. I see that in my friends too, they left group without saying a word, it means FU, don't add me to stupid group chats again. How about events? People start not responding on event invites as well.
So I decided enough was enough -- along with numerous ethical problems of facebook [2], fb does more harm than good to me. In the last couple of weeks, I have deleted my fb account. This time, I don't announce to people that I will be gone, I just silently deleted it. I had enough, I don't care who will miss me, thank you facebook. It is a lie: most of them don't, and if they or I do, we would already have each other's contact information.
Beginning of 2017, I also swapped my top-of-the-line smartphone with a dumb phone, with little to no distraction. Data caps is no longer a problem, privacy is no longer a question (I just assume everyone hears), features is no longer a problem, losing of sleep is no longer a problem, apps definitely is no longer a problem, and I no longer question or have any problem when someone defriends me. I check my emails when I want. I come to people. I no longer have the urge to check my phone for facebook feed in the middle of the night. I lug around a big ass mirrorless camera that takes pictures not for likes and navigate by my instincts. I feel great. I feel productive. I feel creative. I feel freedom. I started commenting on websites that people don't know and care who the fuck I am. But they have the same hobbies and interests, so I feel connected, I feel togetherness.
There is definitely more when I have less of facebook.
0: https://www.google.com/search?q=girl+live+streams+sucide+on+...
1: http://journals.plos.org/plosone/article?id=10.1371/journal....