How does \Magento\Sales\Model\Order\CustomerManagement::create() work?

Context: How does Magento 2 propose a guest buyer to register himself in the store on an order placement?

Details: How does \Magento\Framework\DataObject\Copy::copyFieldsetToTarget() work?
See also: How is «to_customer» aspect used for a fieldset copying?

Instead of loading a new page for creating a customer account for guest , can’t we display the registration form on success page by taking values from checkout page?