That was the way I read it as well. Moderate drinking: possibly beneficial. Heavy drinking: likely damaging.
But in neither case are they saying it’s the only factor, nor that they really understand the mechanism.
It’s not really that slippery of a slope if your drinking “pattern” eventually becomes more conservative. The limits you set for yourself must change as you get older. If you’re at a case and a half of beer every week at age 25, you’re going to want to be down to a case a week by age 40, and by 60 you should still be enjoying your beer at maybe just a half case per week, even if you knock back all 12 in a 6-8 hour period. At that rate of change, you will probably never even come close to physical addiction. However, if you find that you’ve become an increasingly mean drunk more than you’ve been a happy drunk, you might want to cut back a little and by no means should you switch to hard liquor...That shit’ll kill ya!
Genetic predisposition is likely the greatest single factor. I’ve known some high functioning alcoholics who have done very well for themselves in life and I suspect they never truly sober up. That would kill most people. I’ve known others who seem to lose brain cells with every bender, you can just about watch them go downhill. Me, I spent a good decade hitting bars every day of the week, I think it aged me more than I would have otherwise but no medical repercussions thus far. I never did crave it though, it was a social thing for me, never kept it in the house. Did have a drying out period when I stopped that was not particularly pleasant, night sweats, had trouble sleeping. Lasted a few weeks.