No test measures intelligence. A test only measures you relative to the persons that wrote the test. – loosely quoting Asimov.
2007 is ancient history now. It is an interesting graph that one might correlate with a lack of meritocratic structure in society, but I’m on the low end cause I say this without looking up and reading the study. Pretty pictures evoke emotional blabbering bias and all that.
I genuinely thought that was the point of this graph. The logarithmic function in blue very clearly shows there is a limit as to what IQ alone will net you.
People will look at the same graph and come up with different explanations. I personally agree with your interpretation.