Actually it can be done, they can set it up so that the person purchasing can enter the character name of the acct that they wish the gift to go to and the server number. This way when the paypal payment URL gets generated it will auto credit the package to whoever is receiving the gift. However, this does increase the potential for fraud and should not be implemented.
I did not say it could not be done. In said that this is the only way that you can do it now. It could also be set up so that you could purchase gift cards of some sort and then provide the code to the player you are gifting it to.
The opinions expressed on this post are my own as a player, not as a Moderator.