If you don't consider social aspects to be a reasonable argument for drinking, then there is no reasonable argument for drinking. I think the article has to be read in context of how drinking is perceived when discussed in seriousness, which is mostly with sheepish guilt. His argument is, essentially, that the social aspects are valuable enough to justify drinking within reasonable limits. I don't think he argues it's necessary for society to function, it just might be more beneficial than people generally dare to admit to themselves.