I'm not sure I understand your point, maybe we're talking at cross purposes? In the case of chopping off a thief's hand I see the _desire_ to steal as the moral failing. Preventing the physical theft in that case doesn't resolve the moral failing. In the alcohol case, (some) people who take naltrexone completely lose the desire to drink, so the internal _desire_ (or 'moral failing') has resolved, rather than just the symptom of drinking.

But we may be using different definitions of moral failing