AMD has got deals with Sony and Microsoft to provide them with hardware for their new machines. Moreover, AMD could have got a deal with EA for Battlefield 4. This deal had cost between $5-8 million.
AMD would obtain a better optimization for Battlefield 4 on PC and the game will come free along a selection of AMD graphic cards. In the same vein, DICE would have obtained an early access to Mantle, the new AMD tech as a result of this agreement. Battlefield 4 would support Mantle tech in an update this December.
AMD is waging a new war, this time around between the PC users; maybe if you want to enjoy the best features for B4 on PC, you could need an AMD graphic card.
Thanks, VG24/7.