Completely disagree because he has provided reasoning based on personal observation of real-life situations.
That makes it amenable to understanding, evaluation, and practical application by himself and by other people, like me.
The same can't be said for very complex models like MBTI or the so-called "big five" which are difficult to understand and require complex scientific methods to study. Such models may be correct and may be useful, but it would be hard to evaluate their correctness and it would take a vast amount of effort to use them.
That makes it amenable to understanding, evaluation, and practical application by himself and by other people, like me.
The same can't be said for very complex models like MBTI or the so-called "big five" which are difficult to understand and require complex scientific methods to study. Such models may be correct and may be useful, but it would be hard to evaluate their correctness and it would take a vast amount of effort to use them.