Not to sound trite but the problem isn't alcohol it is problem drinkers. Those who can drink moderately do so with any consequential benefits which accrue. Those who can't drink moderately always start out thinking they are drinking moderately but unthinkingly fall into "just one more".

A problem drinker (or a 'seasoned' smoker) cannot partake moderately, they don't know how to stop. For these people the moderate drinking message is misleading and harmful.

Haven't read the book the article is based on because it appears to be out of print in the UK (or at least very expensive) but another factor contributing to alcoholism is a person's capacity to take alcohol. The more tolerant you are the more you drink to get a buzz, and if you are in the habit of drinking heavily on a regular basis then the other health issues - such as habituation - have a greater chance to develop.