I don't disagree with the common tendency to conflate the testing methodology with the actual Jungian system behind it. That's exactly my point, though. None of these online tests can successfully eliminate the inherent bias of a self-reporting assessment and the self-fulfilling prophecy I mentioned before. They're a fun novelty, but they're not something a clinical diagnosis should ever be solely based on. People lie to themselves all the time to get a result they find meets their opinion of themselves / their reality.
Understanding Personality is far more nuanced and detailed than the MBTI can deliver. All I'm saying.
--edit: Here's the INTJ vs INTP coming into play