For many of us, it's not about Puritanical values. We simply choose healthier behaviors.
It's true that the median alcohol drinkers in America doesn't drink much at all. The vast majority of alcohol is consumed by 10% of the population.
Drinkers tend to cluster with other drinkers, and non-drinkers tend to become less interested with attending gatherings that revolve around alcohol consumption. This can lead to misperceptions that either everyone is drinking a lot or no one is drinking much depending on which cluster you end up in. It's strange to hear some of my heavy drinking acquaintances insist that everyone drinks heavily, because that's what they see in their personal bubbles.