My late father was a Maitre D' in the early 60s in the city of Dax, very close to the Armagnac region. He used to say that that one reason Cognac gained prominence over Armagnac was also because the Cognac distillers decided to industrialise in the interwar period, while most Armagnac producers made a conscious choice to maintain small volume due to quality control concerns (and the price rarity brings with it). He also used to say the Armagnac producers just botched their marketing, the the Cognac guys nailed it. Anecdotal of course, but I'd like to hear your thoughts on the hypothesis. (Dad could spin a yarn)