Because the results are not comparable. At all.Two members here just benched borderlands 2 on the FX8150, and their findings are much higher than that website...
They benched with disabled/low PhysX, while the website seems to have that on high setting. If you look at the comparison videos available on the web, PhysX effects are used heavily in BL2 and offer really nice graphical extras. Disabling PhysX means that there are a lot less effects to be rendered, which reduces the overall graphics load, which in turn raises the framerate. Of course the game also doesn't look nearly as good as with PhysX. So what our resident AMD fans "bench" is not really indicative of what you'd want to use if you like good-looking games.
But it's even more complicated; in BL2, PhysX can be run on the GPU if it's a modern Nvidia card. This will take off some load of the CPU, but in turn also impact rendering performance (the GPU can only do graphics OR PhysX each cycle). For a real comparison of BL2 CPU performance needs, you'd need to test it with the following combinations:
Intel CPU + Nvidia gfx
Intel CPU + AMD gfx
AMD CPU + Nvidia gfx
AMD CPU + AMD gfx
And each of these combination would also need to be tested for the different PhysX settings. Only then could we really say just how well AMDs CPUs perform vs. Intels. But for the moment it seems to be safe to say that for real maximum quality in BL2, you're best of with an Intel/Nvidia combination.