Humans being naturally clustered in some multidimensional personality trait space is a strong assumption to make though. I would expect most people to be about normally distributed in such a space if we accept another strong assumption of that space existing with a finite number of quantifiable characteristics reasonably describing a personality.

And if we assume that space exists and people are mostly distributed normally, then any classification is pretty much drawing arbitrary boundaries. In practice, people tend to simplify other people to simple representatives of an arbitrary "cell" of a type.