This is a common misconception that I'm glad to clear up to get things started!

People use the term "personality test" to describe a lot of things, from Buzzfeed "what pie are you" quizzes, to more popular systems like the Enneagram. But strictly speaking, a personality test is any instrument that's intended to measure individual differences. Personality assessments are used in a variety of very serious applications. Clinical psychologists use them to help diagnose mental disorders; academic psychologists use them as a basis for studies on how our traits and characteristics influence nearly everything in our lives, from lifespan to divorce rates to happiness.

So, I hope this helps to explain why it sounds very uninformed to say "all personality tests are junk science." I know what you're trying to say, but the phrasing shows a lack of understanding.

To address what I think you were trying to say, yes, there are some valid challenges to more popular personality theories like Myers Briggs and the Enneagram. One of the most valid issues with these systems is that they sort people into "types," and really, people don't actually sort neatly into types. Personality is more accurately described as traits on a spectrum, rather than types. That's why we love it when people take our Big Five assessment, which measures five major dimensions of personality, and take the time to understand what those traits mean to them.

But that doesn't mean that type assessments are useless. The human brain naturally processes things in terms of categories, and type-based systems are a lot more approachable for laypeople. So long as they have some grounding in real human variation (which all our assessments do) they can be a useful shortcut for understanding fundamental differences.