However I proposed it could happen from number of other reasons and gave example that people do not use Linux for gaming (I could be wrong) in the numbers as before.
It is more likely than your theory that many computers are used for different purposes or are laptops which may not have discrete cards. You forget there that plain desktop uses where present and Intel has been dominant in laptop market for ages. Not only that but Phoronix / Openbenchamrking Users/ Readers are here to get most out of their PC therefore use it for more then just writtting e-mails but in many cases are gamers /video encoders/video watchers/etc. whom need best card for their purposes and it is possible they could ven move away from Linux ergo are not benchmarking their machines in Openbenchamrking
Still I wish I am wrong