Time and effort is required to source the raw materials, everything from wax to drill bits. Add to these factors that fact that pipemaking operations are small companies with few if any employees. Logistics is simply the systemic approach to strategically integrating Purchasing, Operations, and Transportation Distribution. Each new link in the chain adds costs and transactions, each link eliminated shifts responsiblity and costs. These functions are absolutes - the raw materials have to be transported to manufacturing.
Manufacturing has to do something.
The final stuff has to get to the customer. Now you can argue some agricultural products don't have manufacturing, but processing may be involved - but we'd be splitting hairs. Specialization is the key to our economic vitality. The creation of surpluses allowed civilization to trade and lifted us from a hunting and gathering to an agrarian economy. Specialization allowed for mass production.