The author acknowledges the usefulness of such tests, but cautions against the tendency people have to reduce themselves to a set of rigid traits. And I tend to agree.
I personally have found such tests useful at times, and they have helped me understand aspects of myself. In a work setting, they can help teams better understand each other and improve communication.
But there’s also a tendency to take these results too seriously. Taken too seriously, they feed self limiting beliefs. This is in the category of issues that the author seems focused on.
While I had long known I was an introvert, and an MBTI test certainly confirmed that, it took me far too long to realize that social skills still had a major impact on my social life, and that my social anxiety wasn’t just about introversion.
Social interaction drains my batteries, but social skills are orthogonal to introversion and still need to be cultivated. Believing that my social tendencies were modulated purely by my introversion kept me stuck in anti-social patterns for too long.
The truth is that the self is malleable and ever changing. I’ll always be an introvert, but I’m not the socially anxious introvert I once was. This means I do more social things and spend less social energy than I once did.
I know a decent number of people who base daily decisions on how they categorize themselves (or on how they don’t categorize themselves) instead of entertaining the possibility that they might like something. I was one of those people for quite a long time, and I’m still breaking the habit of being me on a regular basis.
These tools are more useful than a horoscope, but if rigidly applied, not by much.