Yeah but if they did this there would be a flood of tears on the Steam forums after a day or so from PC players who couldn't accept that people aren't defined by the computer they use and these Mac players are mysteriously experienced at shooters. Because they clearly couldn't own both a Mac and a PC. Or have run bootcamp. Or have played the shooters available for the Mac.
Anyway should be fun. Time to delete the Windows partition on my MacBook Pro Should free up some space.