Human interaction is messy, complicated and time consuming. So managers who are short on time (or short on emotional intelligence) love the idea of anything that helps sort people into easy-to-understand, data-backed boxes. This is why the employment testing industry is worth $400 million.
Managers fervently hope that pre-employment personality tests will simplify things, providing valuable data to better understand prospective employees, thereby creating decision-making certainty.
But, when you are trying to understand another human being, personality tests are only a crude approximation.
To paraphrase Einstein, "Everything should be made as simple as possible, but not simpler."
Tests reduce a human being into a something that seems more understandable, like a map. But when you look at a map of the Grand Canyon, do you feel like you’ve experienced it? Of course not. Maps are notoriously error prone, subject to revision, and dependent on personal interpretation. If maps were always perfect, the earth would still be flat and the Americas would be labeled, "Here Be Dragons." Cartographers still debate which map best represents Earth.
Yes, maps can be helpful, but they can also be misleading. As anyone with GPS will tell you, a map is not the territory.