I'm not trying to answer for Chris, but I can tell you where it mattered. I was an active-duty Marine in the 1960s. At that time, we had no choice in the occupational specialty we would be assigned to. The ability to independently perform while under stress was critical. The decision process involved testing.

There was the GCT test which was a rough equivalent of an IQ test. MENSA will allow, or at one time did, a Navy GCT score. There was also a battery of aptitude and psychological tests. All of those were used in the decision-making process. Notably, every MOS had a minimum GCT requirement, but it was not the only consideration. If you were qualified for a hard to fill field, you'd probably be assigned to that rather than one you scored higher in. After that, the training was set up for a high attrition where some washed out nearly 50% and reassigned to another field.

It was a highly successful method for getting the right people into the right jobs. The reason for both a base level of general intelligence and aptitude should be obvious since that zeros in on smart for what and able to do what? Over the years I saw people who were smart enough to get a degree in engineering, computer science or mathematics who ended up in management because they did not perform well in their field. The ability to apply knowledge is a big deal. I don't know if that can be predicted with a test other than actual performance.

Sorry that I rambled a bit, but history has shown that a general level of intelligence is required for success in some things although I strongly think that a sharper focus is needed after that. You don't need to go to the level of idiot savant to see that ability is not level across a single number measure of intelligence like IQ.