Earlier quoted context omitted.
No one thinks intelligence is irrelevant to getting a PhD. The question is, how do you know that getting a PhD relies "heavily on intelligence"? How do you know that intelligence has a strong or weak correlation? Or that there isn't some sort of threshold, where an effective IQ of at least 90 is important, but 140 is no more important? What other factors have you considered, and why have you concluded they are less s…
OK, let's use your hypothetical that if we accept everyone, that they will have equal graduate attainment (regardless of test scores). Then, we would expect that there would be little correlation between testing scores and outcomes. Especially whether they get a degree. For instance, someone who gets a lower test score will have the same outcomes as someone who gets a higher test score. But that's not what the resear…
The hypothetical was meant to show that your analysis was insufficiently sensitive, not to posit that the hypothetical was actually the case.
You have an odd habit of pointing to secondary and preprint material, rather than the primary literature. Your APA links to several papers, including http://www.drtomascp.com/uploads/HungryMind_PPS_2011.pdf , titled "The Hungry Mind: Intellectual Curiosity Is the Third Pillar of Academic Performance". It concludes:
> The current study suggests that traditional sets of predictors of academic performance, notably general intelligence and Conscientiousness, should be accompanied by a third factor: intellectual curiosity. Jensen (1998) stated that “[general intelligence] g acts only as a threshold variable that specifies the essential minimum ability required for different kinds of achievement. Other, non-g special abilities and talents, along with certain personality factors ..., are also critical determinants of educational and vocational success” (p. 544–545). A remarkable number of studies on determinants of academic achievement have focused exclusively on ability and effort; the present findings, however, recommend further expanding the “g-nexus” for a better understanding of individual differences in academic performance. The latter requires—beyond intelligence and effort—a hungry mind.
It does say "intelligence is the single most powerful predictor of academic performance", then said:
> intelligence sustained the strongest effect on academic performance with a path weight of .35. TIE and Conscientiousness had slightly lower, identical path parameters of .20.
I believe that means that the other two legs together are more important than intelligence alone.