Quake 3 really isn't a good measure though. The game is almost, what, 3 years old now? There are games that even a g4 can't run at 85 fps at 1600x1200 (especially with FSAA engaged). Heck some of the newer games I can't even pull 40 fps with a g4 at those settings. So the power does matter, just not if you are playing really old games on your computer.
Also, 3dfx only went belly up about 2 years ago. Since then we have had advances, and not just in raw power. Look at the directx 8 features, there have been real advances.
Don't forget why 3dfx went out as well. They started releasing products that were not keeping up with the competition. For a while they could do this, they had glide entrenched and a huge market advantage. But they could only get away with it for a couple cycles. The TnT put Nvidia on the map, the TnT2 really put them in the lead position, the original Geforce put 3dfx in a coffin and 3dfx's 'come-back' card (the V5) was 6+ months late on release and didn't compete with Nvidia in price OR performance. Game over.