In a perfect world, yes, the producer controls the amount created and the specified price of the product, but the article mentions that producers sometimes sell

In a perfect world, yes, the producer controls the amount created and the specified price of the product, but the article mentions that producers sometimes sell to one market for more than another. If the delta between these two costs is large enough, these "simple middlemen with no value" step in and earn some money. I don't see any reason for Amazon to crush them - Amazon is getting a cut of their profits and they effectively outsource all liability to another company. I also don't think they're simple. They've identified a constant in our world - inequality in either income or product, and they're exploiting it for the (arguable) benefit of the consumer. What they're doing takes experience and connections (to the logistics & supply chain) and it takes intelligence and engineering (to predict supply/demand and price appropriately). Do I think these guys are inventing a world-changing technology? No, but let's not underestimate - they are far from simple and they will likely never go away.