I don't believe personal responsibility and willpower is a fixed quantity, even at the population level. In fact, I think they are negatively impacted by emphasizing the influence of external factors in personal behavior.
Telling an addict that they are powerless to regulate their consumption only erodes their ability to improve. External factors my have led them to their addiction, but they can't fix an additional without assuming agency taking control of their behavior. Yes, this is HARD, but no addict can recover without it.
The only durable solution that will help people is shifting the curve such that more people are able to resist or avoid addictive activities. Policy solutions are simply too ineffective and porous to have a durable effect.