It's not really. It's not a hard science like physics, but even physics was mostly based on guesswork in the early days. And the mind is a lot more complex than basic cosmology.
Early physics pretty much was pseudoscience though
I also agree that the test is rather bad. Many of the questions are kinda transparent, and IIRC Jung is considered pseudoscientific by psychologists.
Introvert(44%) iNtuitive(25%) Thinking(75%) Perceiving(67)%
You have moderate preference of Introversion over Extraversion (44%)
You have moderate preference of Intuition over Sensing (25%)
You have distinctive preference of Thinking over Feeling (75%)
You have distinctive preference of Perceiving over Judging (67%)