What is the purpose of a personality test?

Because of their interest amongst respondents, popular personality tests' validity is often researched and studied. For example, the famous Myers-Briggs 16 personalities test has received criticism due to its black-and-white nature (you are either an introvert or extrovert, judging or feeling, etc.). While some may critique the idea of putting individuals into defined categories, others still believe in the insights such categories can provide. Specifically, in the workplace, such insights can lessen the risk of placing candidates in the wrong role and give employers the ability to understand better what motivates and drives their employees.