Why the hell would I buy Bitcoin to buy stuff on Amazon through a proxy site that sells my BTC for me instead of just... buying on Amazon like a normal person? BTC will be way slower and more expensive than just using my credit card... Plus Visa will refund me in the case of fraud.
Like I side, speculation is the only thing you buy BTC for (moon!!!111), and the exchanges will prevent you from doing this if you are related to blacklisted accounts.