Meanwhile Nvidia is quite happy to not only force a VendorID lockout but to also turn it into an advertisement for their hardware. If you wish to unlock this feature, buy Nvidia.
The only evidence we have is that there is a vendor id enabling. Which is not the same as a lockout. And the fact that Nvidia is somehow forcing this is merely an assumption for which there is no evidence, let alone proof. I think that it is a pity that there are many otherwise reasonable people going even further and basing all sorts of conclusions on this unproven assumption.
Fact is that we do not know why the developers put in a check and how it works. We have only testimony that AA appears to work properly in superficial testing if you alter the vendor id on ATI hardware.
Aside from being blamed for something they may very well have no control over or hand in in the first place, I can't help but feel that Nvidia just does not get much credit for providing a first class ecosystem around their hardware. For me, enjoying videocard ownership is about more than x FLOPS for y money. When it comes to game compatibility and features, OS support, added value (yes, including Physx, and CUDA, and OpenCL that actually works), general hardware availability, choice of vendors and other factors, they're doing really well. So what if Jen Hsun Huang is a batshit crazy egomaniac with less vision than Stevie Wonder, I'm still happy with what they bring to the table.