That's not what they're saying. The point is that it's easier to say something about the past with the benefit of hindsight than to say something about on-going action. How would you prove that positive selection for these traits exists right now? What kind of evidence would that take?
I see, yea I misunderstood. Thanks for the clarification.
The question is whether some specific genes are still being selected for, and the answer is not obvious, though it's a good bet that if they were, and if we're seeing a rise in incidence, then they are.