The combo of built in and also discrete graphics is a relatively new phenomenon for them.
I remember back when they introduced the first MBPs with the two different built in graphics chips they were hyping it up, but the audience reaction was stony to say the least, because the previous MBPs had had a moderately good (for the time) graphics card, and built in graphics were perceived as being of a much lower capability, so that was a step backwards in power.
It might have given them great battery life (I seem to remember that as their big selling point), but it meant you couldn't play graphics intensive games on them.
I wonder if real-world gaming benchmarks will really have near the promised 3x improvements over the last gen MBP's...