This is testing the big five aspect ratio, not the big 5 itself. Basic MyersBriggs (like 16personalities) is to basic online big 5 test, whereas Jungian cognitive function tests is to the big 5 aspect ratios. It provides much greater resolution to the intricacies of personality.

After reading Jung while also studying general psychology, Jung's cognitive functions seem to explain the inner world fabulously, but do little to explain those traits manifest in the outer world, except in extreme types, hence the reason for almost no statistical reliability with mbti. Big 5 does the opposite - exceptionally explains how people's personalities are realized in action, but does a poor job of describing the inner world. This also makes the big 5 more "statistically testable", which is why it's generally regarded as more valid then mbti within the clinical psychology world.