Buyer pays via Paypal and wants item shipped to Nigeria instead of their home address registered with Paypal (in this case UK)
Person in Nigeria receives item and informs the buyer.
Buyer opens dispute with Paypal stating they did not receive their item and demands a refund.
By sending an item to an address other than what is registered on Paypal, the seller has no protection and will invariably have to cough up the money to pay back the buyer.
Seller will be out of item and money.