[kobenni]

The distribution of the data is also the main problem with MBTI, AFAIK. Intra-/extraversion for example have a unimodal distribution with most people being somewhere in the middle. And exactly that middle is where MBTI makes the cut on their classification.

[kelseyfrog]

This is a great point. We have a generally tendency to typify in binary[black and white] terms. It overrides our ability to express nuance and un this case pushed out a larger category (if we even wanted to still categorize) of ambiverts.

MBTI speaks more on our drive for categorization than it does on the people being categorized.