Many organizations believe that the most effective way to run an organization is to construct the flow of information from the top down. This leads to an environment of silos. The problem is that silo is not the way the processes flow. They are constructed in a chain with each link of the chain feeding the next one.
All processes begin with the creator of the component of the end product or service which when combined with other components result in the product or service which you deliver to your end user i.e. the customer.
Think about the mountain stream. The water flow down pulled by the pull of gravity. In rare circumstances the flow may be in reverse but it is always in a continuous flow. In the supply chain that flow is always horizontally. Your suppliers contribute to the process through their inputs which flow to a process. The process flow into an output which flows into a finished product or service. The final stage of the process is the delivery to the customer the product or service they have purchased.
This is a clear argument for the removal of organizational silos. They are the bane of your existence.