There are a lot of people here of the opinion that his parents just should not have let him access it, but aside from the difficulty of preventing a 17 year old

There are a lot of people here of the opinion that his parents just should not have let him access it, but aside from the difficulty of preventing a 17 year old from accessing a legal and public website in this day and age... a similar situation could just as easily have happened to someone one with the same mental and emotional problems but one year older. Sure, most people can separate bot roleplay from reality, but there's always going to be a percentage of society, equal to thousands of people, who are prone to seeing messages, communications and emotional meaning where there is none intended. This ranges from slightly magical thinking and parasocial relationships to full-on psychotic delusion. I think within the next few years, we're likely to see cases in which mentally vulnerable adults commit violent acts against themselves or others after forming a connection to a chatbot that inadvertently mirrors, validates and reinforces their distorted thinking.