"...America's crush on size continued well into the 1970's. Many attribute its demise to an article...by Frank Prial..."

Frank Prial wrote a huge number of articles concerning wine in the NYT in the 1970s and perhaps somewhat longer. The NYT has archives on line, and a search of these from about 1970 to 1985 for Frank Prial likely would turn up the article, if online archives for that time period exist. Also you might try to contact the present wine writer at the NYT to see if he/she knows something about your question. I would not be surprised if there are hundreds of articles by Frank Prial, so this search could take a long time, even if all of his articles are available online.