The makers of fine wines and whiskeys have been blending for years in order to provide a more uniform and predictable product. This does not mean that they dont also have offerings from a single barrel or from a single grape varietal in a single field. Its just that sometimes a group of distillers and grape growers will collaborate in order to benefit them all.
When does it make sense to employ a range of suppliers and when would such behaviors raise eyebrows if not the ire of the customers? Try to characterize the difference and provide an example or two.