Comment by teshier-A

Well it does sound reasonable but I don't think it is as convincing as OP thinks. If you take two IQ tests in your life and get 130 and 138, I imagine the variation to be higher than the group vs group comparisons he mentioned (maybe not doctor vs craftsmen? it is after all very correlated to education level) but it doesn't mean the measure is "nonsensical and ever-chaning values such as whether I liked today's dinner.."