When an assertion about a type conflicts people's experience in reality, instead of refuting the assertion or counterexample, they modify the subject of the assertion.
All INFps enjoy literature.... Maggie doesn't enjoy literature and types INFp.... Well all true INFps enjoy literature, Maggie isn't one of them.
The entire science is built on this fallacy, people make baseless claims on what constitutes a type and in order to uphold these claims they type people differently rather than actually attempt to refute the assertion or counterexample. Any attempt to form consistent claims with reality is considered to be "overly scientific and unfun" so instead most people's understanding are fallacious collections of stereotypes which contradict each other, when confronted with a counterexample to the universal claims with which they categorize types, instead of attempting the reconcile the counter-example with the claim or modify it, they immediately turn to re-typing or type-doubt.
Of course the moment someone mentions socionics as being bullshit or mentions an XXXX type, gradients of dichotomies, or type change, everyone gets extremely serious and scientific about their justifications, and its no longer about "fun" but something much more serious.