While violence or extreme acts may not be on the rise, what about depression and anxiety? The victim may be the person exposed to the content, not who they in turn harm.
I'm not making the claim, I'm offering the question whether more research is needed to determine if the exposure of extreme material increases the level of depression and anxiety a subject may experience.
I am simply responding to your statement which seemed to conclude that only violence and extreme acts are the only measure to determine if something has a negative or positive impact on society. I do not believe it is the only measure, so I posed the question.