It's true by definition because MBTI splits people into two groups, four times in a row. Everyone is going to fall into one bucket or another, just as the last

It's true by definition because MBTI splits people into two groups, four times in a row. Everyone is going to fall into one bucket or another, just as the last 4 bits of any integer is going to be one of 16. The question is whether the distinction has any practical uses. My guess as to why MBTI is more popular than other equally valid personality tests is that the splits are defined in such a way as to capture a few traits that people find the most irksome in their everyday relationships. You want to take a rational approach, but your SO gets all emotional? Well, that's a T vs. F thing. It might not be medically meaningful, but IMO it does help us appreciate that other people's minds might be wired differently. Not wrong, just different. Business idea: AI companions with custom personality out of the box. Choose the MBTI type you want!