How does it follow from that that it's not also facebook's fault? If the government and parents are failing to prepare children for dealing with the adversarie

How does it follow from that that it's not also facebook's fault? If the government and parents are failing to prepare children for dealing with the adversaries that they encounter in life ... does that mean anyone who is using that lack of preparation to their advantage while knowingly hurting those under-prepared people cannot possibly be at fault for their actions? If a child hasn't learned about the dangers of drugs in school or from their parents ... does that mean that someone selling them hard drugs cannot be at fault for making money from that situation?