Instead of re-examining the system in place, they choose to link it to mental health. And, even if he has some sort of mental health problem, why not examine the events that led up to that?
What about the person's background, family, abuse, etc? socio-economic class? Was he raised in a household below the poverty levels? Did he have enough food in his development years? if not, it might have impacted his mental development hence might have resulted in mental illness in teenage years. This is merely one example.