well, why not indeed? One would be paying with money or am I missing a point here? Person A has bitcoins. Person A want’s to purchase item. Person A has the option to purchase said item using said bitcoins by using a card that takes care of the conversion.
If you were a traveling man, wen’t to a foreign country and wanted to purchase an item, would you have issues using a card that is tied to your hard earned dollars instead of say going thru the hoops of getting cash, converting to the native currency? Would you ask the same question?