In the USA, funding for treatment usually comes from different sources. One fund is marked for addiction treatment and the other is for mental health. That makes it very difficult, especially for treatment programs, to provide the comprehensive care that addresses everyone's needs.
Because the history of funding started as distinguishing between mental health and addiction, it was a surprise to many that treating them separately doesn't work. There are still programs that address only alcoholism, or addiction and others that only address mental illness. In many cases, clients go to one program for addiction recovery and another for mental health treatment. The client then has to figure out for themselves how to make that work for them.
Treatment needs to focus on all the problems clients are facing. It doesn't work if we don't address physical, emotional, mental, spiritual, social, financial and family needs. If someone has a broken arm and gangrene on their feet, it's unethical to only treat one of the problems. Someday people will be treated as if any problem affects the whole person.