Why don't we automate the entire Procurement and remove the human element?

Technology already has the capability to perform the entire procurement function from Supplier on-boarding, sourcing, contract management through to order placement. Human interaction introduces risk from errors without necessarily adding additional business value. As technology increases its capabilities it is able to automatically undertake more and more complex procurements so why do we still need humans to be involved? If your answer is because of the complexity of the procurement, that is not good enough!