Everybody releases to the strongest, most stable personality. That is the surest way of 1) releasing some of that incredible nervous energy that is built up and 2) making sure that the system survives. They sure can't go off on the addict because who knows they could end up losing all the grocery money for the month.
Here's my take on the subject: Every group of people is a system. Every individual has to take on certain rules and responsibilities in order for the system to stay organized, efficient, and even survive. So every family (dysfunctional, not dysfunctional, and everything in between) has individuals in roles. But the more functional families allow for the individuals to move in and out of the roles. Such as, let's say the oldest child matures and becomes less hyperactive, less of the acting-out child then that leaves an imbalance in the system and, lo-and-behold, another child moves out of their role and into that hyperactive, acting-out child. Mind you, in the more functional family the intensity of these behaviors is very manageable by the parents. So at some point even the youngest, who is usually the class-clown type, is able at some point in their childhood to move out of that role into something else and the family does not shame them for that.
The more dysfunctional family systems use shaming techniques to keep the individuals in their roles. That's probably because the roles are so rigid that nobody else can move into the vacated role. That's a fear thing.
Mind you, all this is on a very deep level in the brain. Nobody is even aware this stuff is happening. I bet teachers see it all the time. You get a class full of kids on the first day of school and see how the kids play together. Then go back a month later and see the difference as everyone has "found" their role.
So that's my take on it. Take what you want and leave the rest.