I somewhat see your point. However when a game is released for PC and MAC they don't make you pay for the game twice... you can just simple download the client for both platforms and play on either.
Anyway thanks for the replies.
Despite what Apple may want you to believe a Mac is a pc, aka personal computer. They are the same thing just using different operating systems. A PC and PS3 however are apples and oranges, you may play games on both but they are wildly different and thus warrant needing to buy a different copy for each system.
This one time at FFXIV camp I tried to get a 3 person party going, but just ended up as a Disciple of the Hand.