What's the point of "restitution" if it came from the victims anyways? The Sacklers would have kept all of their ill-gotten gains under this settlement. The amount they'd be paying is practically just the interest from their earnings.
I have a hard time with the concept of retribution alone, but I think if it is phrased in terms of modeling societal standards and demonstrating to others that this behavior is unacceptable, it is still valuable to society. I guess you can mark that under "deterrence", but it's less about sending a signal to future would-be criminals, and more about communicating and demonstrating societal standards to the entire society at large.