They felt like dumb failures, having been officially branded as such be science, and their motivation to study naturally plummeted. It was not until 1974 that the public education system was finally reformed. Intelligence testing enforced political and social prejudice. And so abuse and test bias controversies continued to plaque psychometrics. Measurement is fundamental to science and technology.
Science often advances in leaps and bounds when measurement devices improve.
Psychometrics has long tried to develop ways to gauge psychological qualities such as intelligence and more specific abilities, anxiety, extroversion, emotional stability, compatibility, with marriage partner, and so on. Their scores are often given enormous weight. A single IQ measurement can take on a life of its own if teachers and parents see it as definitive. It became a major issue in the 70s, when court cases were launched to stop anyone from making important decisions based on IQ test scores. The main criticism was and still is that current tests don't really measure intelligence.