'Cluster effect' crucial to a wine region's success, say researchers
Well, there IS that . . . the concept of "critical mass." If there was only one great producer of, say, Priorat, then would people be trying all sorts of different producers there -- and in Montsant? Probably not. (After all, how many people know Chateau Musar, for example? A lot, but of all of them, how many can name two other producers in the Bekka Valley?) But with a number of great wines/producers of Priorat, there becomes a higher level of name recognition in the broader marketplace as a whole, and so more and more people seek them out .
Then there is the idea of a (e.g.) Comité Interprofessionnel du vin de Champagne -- a group of producers that serves to promote ALL the wines of the entire region, while each member producer also promotes his or her own wines. The "Douro Boys" is a similar type of group.