College grads average IQ had dropped from 119 in 1939 to 102 in 2022. For many jobs an IQ test would be sufficient to determine expected likelihood for long term success. College still teaches domain expertise but to a larger and less intelligent cohort - so I would attribute the lower value of degrees more to it's decreased relevance to general intelligence. Which would suggest the very thing to fix it would be through the use of IQ tests, but we're not allowed to do that.