I suffer from PTSD due to childhood abuse and neglect (and I'm talking heavy drug use, physical, verbal, and psychological abuse, gas-lightning). But when my parents, my abusers, added me on Facebook I felt obligated to add them due to pressure from family members and friends who don't get how the abuse affected me, and out of guilt because I had a child and didn't want to deprive them of some relationship with their grandchild. I do know that responsibility lies with me for not ignoring them or speaking up about it. However, leaving Facebook severed that connection again, and I felt slightly more free knowing I wouldn't have to interact with them or let them have a view into my life.
I started using Facebook because I wanted to cure my loneliness and make some friends in college, which did actually happen. At first. Now it's just a platform that reminds me of the past by forcing these "connections", suggesting people who I had long forgotten and never wanted to speak to again.
I say, "Good riddance".