Quote: The Avenger "OK how about another one
Tackler comes in at sternum height and ball carrier rotates his hip to lead with the shoulder of the ball carrying arm making clear contact with the top of the defenders head causing a concussion.
Who’s fault is that?'"
If he led with the elbow then the attacker is at fault.
Clearly I'm not a ref but I get what you are saying. It's not easy to make it black and white but they are trying to make it so to make it clearer.
If the defender 'accidentally' hits an attacker in the head in the act of making a tackle, unless the attacker makes it impossible not to, then it's careless at best but still warrants a sanction. Severity being relevant to the circumstances.