The opposite effect (generated by one wanting astrology to be false - and there are plenty of reasons for that inclination also) might also be afoot.
The desire for your beliefs to be true also affects scientists and biases the scientific enterprise. That doesn’t mean science is not reliable. Same applies here. The bias exists, it doesn’t mean that the results are useless.
Replace MBTI w/ astrology in this sentence.
And just like astrology, you want MBTI to be true so it influences your answers on the questionnaire. Kinda like a Ouija board.