there can be a number of reasons
1. because they can
2. because hardware is accelerating pretty fast
3. because it encourages more intense competition, which means more people use the product. that possibly means more money for them.
Hopefully this one is a little less biased than 3dMark05, which undoubtedly favored ATI. I also hope this one takes the CPU into account a little more than 3dMark05 did, because the CPU has a lot to do with the system and in 3dMark05, a 6800GT would get pretty much the same score whether it was paired with an Athlon XP or Athlon FX.
Yes, I scored 5500 on 3dMark05 with my X800 Pro but only scored 5100 with my 6800GT. However, my 6800GT totally wiped the floor with my X800 Pro and tossed it out to rot! 3dMark05 was ATI biased all the way. Thats also why ATI fanboys will never stop bragging about their 3dMark05 scores. They don't mention 3dMark03 which is a much better benchmark.
Hopefully this one is a little less biased than 3dMark05, which undoubtedly favored ATI. I also hope this one takes the CPU into account a little more than 3dMark05 did, because the CPU has a lot to do with the system and in 3dMark05, a 6800GT would get pretty much the same score whether it was paired with an Athlon XP or Athlon FX.
But cpu dont account for much when it comes to 3d graphics. is called 3dmark not overallperfomancemark. In game cpu wont help u much, as long as u have a p4 3ghz or amd 64 3000 u fine.