There's a couple. Some samples: * If the hammer manufacturer decides not to sell you any, you'll still have hammers. * If the hammer manufacturer gains enough

There's a couple. Some samples: * If the hammer manufacturer decides not to sell you any, you'll still have hammers. * If the hammer manufacturer gains enough power to fix prices, you won't be paying them exorbitant prices. * If the hammer manufacturer or their country gets embargoed and you're unable to legally purchase their hammers, you'll still have hammers. All the above grant you a strategic advantage since you'll still have the necessary tools to continue your business while your competitors won't (or will have to pay much higher prices for their supply of hammers).