Radeon suck. All versions except 7000 (that we don't now for sure), they have bad OGL (so many errors), bad offload for CPU (they need more CPU performance), bad code morphing and bit manipulation (not good or many emulation instructions). Personal experience: RIFT with Wine, Core2duo SSSE3 CPU@3ghz, Radeon4670@500gflops: 15fps(low quality renderer), 18fps(hight quality renderer - low settings). With an Nvidia@500gflops its 25+fps. Nvidia loads more graphics, wile CPU is at the full on both.
Actually somebody is at fault, it should "just work". Since it's not and the user managed to use the "wrong" driver, somebody in the chain that provided him with the driver is at fault.
First your ati experinces are very old, they are not what the amd blob is today like somebody posted...
But my main point is, that assumption can only than be true if you really dont care at all if you have a free or a nonfree driver. And its not only a question of philosophy or so, I as example have installed the latest alpha from ubuntu but even after that are betas, and there are other linuxes with unstable versions too, so I can be shure zu 99,999% that the grafic driver with the kernel even if its not a "stable" kernel will work, on the other hand there is a big change that a blob will not work because of X or the kernel... even with stable ubuntu version you sometimes dont get a good experince with the blobs... then you maybe have to wait a few months on one api change I think nvidia and amd chocked nearly a year or so before they fixed it. that can happen again in the future...
And then you have to use your card only a few years and then buy a new one, because at some point they stopp supporting them and if you then update your linux they will not work... they even can say tomorow, because linus insultet us so much we stop linux support at all, and after the next api change in X you cant use their drivers or newer distries at all...
So you cant just feature compare free drivers vs non free drivers, you have to see that free drivers is a feature itself...
you now maybe will say thats not that so important than that I cannot play games, thats maybe true for you, but to do so as if a free driver is no feature at all is stupid...
This can easily be fixed... And you just give an random nvidia card, but fail to provide the nvidia graphics card information. Anyways, the real reason the graphics card you mention fails on linux to perform just as well is that there is not enough end users who provide viable information to the developer.
Yet again, the issue is not the binary driver. It's also neither AMD nor nvidia... It's all about how many users are able to return reasonable bug reports that will enable the developer ( AMD, NVIDIA, and whoever else writes drivers) to be able to fix the bugs.
The only person who can be best described as at fault would be the beta testers and end users for being unable to write good bug reports. The developer is powerless to fix bugs unless they are given the correct information to be able to fix the bug, and it definitely helps if you can get things to where you can reproduce the bug on two or more machines.
the fglrx blob sucks, the nvidia blob sucks.
the radeon driver rocks.
Blobs suck, FOSS kernel drivers rock. End of story.