the original intel macs had intel graphics chips integraged. they are crap and found on the cheapest of the cheap windows PC's.
That's not true. Cheapest of the cheap windows PC's come with VIA or worse chipsets, more than likely with AMD CPU's. Intel computers are generally low-mid range offerings due to the price of the CPU and chipset.
OpenCL needs a good graphics card which means ATI/AMD or Nvidia which have their own software to get the most from their products. Intel just writes a basic driver.
Intel writes good drivers. They just concentrate on making the drivers stable rather than fast. Most people prefer having stable computers than trying to get an extra 2-3FPS on an unstable one. The main problem with intel graphics card is the hardware itself, but it is designed down to a price.