This is another valid aspect. Jakub's initial article stated that, for instance, Gearbox were there because they were very happy with the support they got from NVIDIa in making the shader work well on the FX series. But the question should also be asked why does that type of back end support need be required? Also, were they not happy that they "Just worked" in the first place on ATI hardware (assuming it did)? Which is better for the developer - having hardware that does what it says, or having lots of support to on the software end in order to make the hardware run at a rate they are targetting?