To offer a few datapoints here… I do see more moderated drinking in UK/European people in their early-twenties. Even when alcohol is free/cheap, people seem to stop well short of being drunk.

I also see people make a conscious active decision to alter their states of mind. Say for a particular party, or for a particular sunny Sunday afternoon. And alcohol is normally only a small part of the picture in this regard.

I suspect any study that only looks at alcohol consumption is going to see a very limited view of any overall social trend.

I would be very interested to see data about drug consumption, broken down by substance, alcohol included.

Edit: this could also be seen as a regression to the mean. UK drinking culture has been a bit extreme.