There’s a Know How or How To (I don’t remember the name of the YouTube channel; EDIT: @executivechimp@discuss.tchncs.de found it. The video is linked in their comment) that explains why we used to believe moderate alcohol consumption is healthy.
Turns out, those surveys only ask “How many drinks do you have a week?” Notice they tacitly ask about the present, how many drinks now and not in the past. If you were a very heavy drinker in the past and got sick from it, you likely stopped drinking altogether.
Not only that, but people with chronic illness many times choose to not drink at all.
These two populations (sick ex-drinkers and chronically sick non-drinkers) make it seem as if not drinking is not that healthy. But remove those groups from the data analysis or control for past alcohol usage and pre-existing conditions and you end up with a clear pattern: drinking alcohol in any quantity is unhealthy. The more, the worse.
Sorry for the lack of sources; I’m on mobile. I think there’s a WHO report titled “There’s no safe amount of alcohol” or something like that.
That’s it!