In the disease model of addiction, it is nice in that it counters some of the heaping moral blame. Blame the victim is fairly standard in the good old USA, another self defeating philosophy amongst many. You can find a few articles on line about the disease model of addiction and free will.
The good old USA, we have a kind of wacky political bifurcation, either you follow that party line or this party line, and neither the twain shall meet. Either you believe in personal responsibility and ignore other social factors, or you look at other social factors, and you don't harp on personal choice. I feel like you can do both, and we don't need to entrench into partisan sniping.
The physiological element to addiction makes it very rewarding, and to quit is hard, mere exertion of will doesn't really make it so.
In Buddhism, we work to transcend our conditioning and not be reactive, to be creative. There's probably a percentage of free will, creativity, and we're looking to increase the percentage.
There's a lot emphasis on improving condition, creating the conditions that will lead to enlightenment. Improving conditions is an important way of working towards moving toward enlightenment.
Once someone is addicted, and you have the cycle where more and more is required to get the high as you habituate to the drug. Moral judgements don't stop people from using, it contributes to feeling bad about yourself and that leads to more use. Recovery has to be a choice, moving out of attraction and not just avoidance.
There's also a generic element in our genome. Before for water treatment, putting wine into your water killed bacteria and having the gene helped you to survive.
Addiction is very complicated. Free will and blame are in an interesting dance with the issues of addiction.
My first philosophy class was about free will. The Christians who want it because they need it to solve the problem of evil were heavily invested in it. How can an all knowing and all powerful god make something bad happen. The answer is free will. But if you don't have that commitment, the need to have it is less. On the other side, the materialists, who think only the stuff of physics exists, they have a need to defer to physicist, which is a much more muddy picture at this point, but could be an anti-free will position, determinism.
I like the idea of free will, even if it's not true, at least psychologically. Focusing people on their choices can help one to actually reflect on them, and in error analysis. If determinism is true, then I can't help but like the idea of free will.
The magical thinking involved in substance abuse is amazing. Working with substance abuse is interesting in that often times mental health professionals want to ceed that territory to substance abuse counselors. There are some that cross over, and the MICA tradition addresses both issues.
BTW, my sons interrupted me a million times while I was writing this post, so I apologize for any incoherence.