Psychologist measured that people differ by personality, and can be roughly grouped into 16 categories based on traits. I used to think everyone was more or less the same. I'm not sure if 16 is the correct number. But my understanding of the world has been helped by the concept that there are people that do and act in particular patterns. For example some of the battles on twitter that are going on, are just extensio…
Are you by chance referring to the 16 Meyers-Briggs types? It's been claimed that it's less useful than it is popular: https://rationalwiki.org/wiki/Myers-Briggs_Type_Indicator
Knowing that someone is more neurotic than 99% of other people, would seem on surface be useful in predicting how they might react to new or novel situations.