It seems like you are stereotyping people with mental illness as being inherently toxic. Let's not blame poor behavior on mental illness. I am someone who has been dealing with mental health for a very long time. It is a choice to be toxic, mentally ill or not. People can get angry during a game and never hit enter to talk. I've gotten upset and never afk'd or intentionally fed. Poor behavior is a choice, and is not caused by mental illness. Most people who get chat restricted, suspended, or banned, come onto these boards to claim they didn't deserve it, not because they are "crazy" and don't realize that what they did was wrong, but because they have a different mindset that justifies their behavior. Their logic and reasoning that because someone trolled in their game first, they get to. Or someone was toxic to them so they can do it back. Someone on their team was playing badly so calling them "useless" was constructive criticism. It is a not a psychological disorder, but a learned behavior that they probably picked up in their childhood, or from their parents. It is a mindset that needs to be unlearned, not through therapy or medication, but through self-reflection and growth. Therapy may help with this, but it is not caused by a mental illness.
My mental illness causes more intense emotional reactions, which you would think would lead to several instances of toxic behavior and punishments. I was chat restricted once, for telling a griefing player to "learn to read" and called him "bronze." That was my decision, and I have since dealt with the consequences, and I am much more aware of how I use my language in game now. More often than not, my mental illness has caused me to play badly after someone was toxic to me. Someone calls me "useless" and I am suddenly feeling like trash and playing like trash. When people choose to be toxic, it ruins the experience for everyone. Including the mentally ill.