There's actually a large exclusivity-style fight going on in the GPU world. It's not as bad as the console style exclusivity but when you develop a major game you often have to choose whether you invite Nvidia or AMD into the process. They'll frequently pay money and/or provide you with advanced middleware technology, resulting in games that perform much much better on the chosen vendor's GPU's. There are even features that are specifically designed to perform horribly on the other vendor's cards, making them de-facto exclusive. Usually it's unimportant stuff like special stuff like Hair simulation but Cloth simulation or advanced shading can feel like real differences in fidelity.