My experiences are from the "good old days," when I was flight crew on TWA 1964-90. Company policy was for the cabin crew to "pour generously" in First Class, but coach was purchase, limited to two little bottles, plus one wine at meal time. On International the boozed flowed in first class especially, and even in business class, but not in coach.
Never heard of a problem in those days, although I suppose there were some.
Since retirement, I have flown as a passenger a whole lot until perhaps 4 years ago. Again, I didn't see issues like described.
Personally, when I was on first class from JFK to MAD, or wherever, the fantastic meal service would have been dreadful without at least the generous pourings of fine wines.