I'm surprised the author doesn't ponder the following: Perhaps higher IQ means a person has more ability to solve these sorts of problems, if they take the time to exert the effort. That ability doesn't guarantee success in these sorts of questions without applied effort, however.

That would mean IQ is still very, very important. But that it is not the only importans factor in solving problems well (eg rationally).

To me, that seems quite plausible. Not sure why the author takes a rather anti-IQ slant as opposed for promoting supplemental measures.