there you go again - perfect example. "Drinking in excess" - in excess of what? According to who? "Excess" is defined differently across different nations, in some one beer or more is excessive, in others half a bottle of wine at dinner is fine.
Also, it's not "a book" that says so. The author is not just making up some arguments on his own. It's backed up by years, decades of rigorous scientific research with hundreds of thousands participants, in fact going all the way back to 1930ies studies by the same scientist who was first to discover smoking was linked to higher mortality - studies that were mostly ignored for decades.
The fact that drinking in "moderation" has substantial positive overall effects on health is basically widely accepted in medical and scientific communities. The fact that "moderation" is not at 1 drink a day on occasion, but in fact extends to 2-3 or even 2-4 drinks also appears to be actually well accepted based on some of the literature I looked into, after reading the book - in fact much of the community is trying to figure out detailed mechanisms now of these benefits, rather than where or not they exist - that fact is long settled, even though not well advertised.
I approach this question as a scientist, and there is a lot of misinformation and misinterpretation, and of course push-back which comes from press, bad policies, and advocacy groups.
It is somewhat understandable why some people resist accepting the fact that 2 or 3 or 4 drinks daily (slow, with food, low-ABV) is actually better for you than drinking 1 drink or not drinking at all - they fear that risks of drunk driving, bad social/immoral behavior or escalating 3 drinks a day into 20 (alcoholism) outweighs the health benefits. But it's akin to outlawing or severely limited all cellphone use because some people like to text while driving - makes no sense.
Assuming most of us can drink responsibly without operating motor vehicles, and assuming that 3 beers does not automatically lead to 33 beers a day - what is "moderate" drinking amount that maximizes health benefits? I guess this is the question I am trying to ask, and all answers point to: 1 beer is better than 0, but 2-3 is even better, and even 4 is still good. This is in strike contrast to "accepted" wisdom of - any alcohol is bad for you, but maybe a drink here and there is Ok. But no more than 2, because then it's really bad for you.