I take MBTI as a useful tool, not as a label that defines and redefines me. I believe NTs have it somewhat difficult because not all of us are maths and physics masterminds. My best approach to animatronics is origami. That's is what at first made me doubt about being INTP. But there's no way I'm F, because I'm a piece of rock. A friend used to say my heart was like Neptune's nucleus. In enneagram I score 0% e2. On the other aspects, I'm sure about my type. I ADORE being alone, the silence. My mind is set on RANDOM, Ne is what I like most about myself. And finally, I'm Khaos. I can live in a room with no visible floor, full of papers, packages, clothes, I believe in Calvin's "last-minute-panic inspiration".
It is true that it's too easy to manipulate the results, or believe that whatever we're living now is "the real we", hence obtaining different results. It also happens (don't know if it's just me) that the tests available construe types based on simplistic/stereotyped ideas, and that the statements that the tests present aren't specific enough, so, in my case, I'm often self-debating them, analyzing myself deeply, and the completion of the test takes hours.
The friend that introduced me to MBTI also scored as INTP (and 541 sp/sx in enneagram) and we're basically the same person, only that he likes reading about the space and I like reading about art, so I'm confident that I'm an INTP (or that we both mistyped ourselves).
As for the "Type Me" threads, I adhere to the explanations others gave: it seems to be useful to understand what others see, build a more panoramic view of types and functions and apply it to people you meet.