People knowingly keep flawed categories because they enable action.

Evidence

Indeed, apart from such evidence, most of us can think of instances where we have sought to maintain our view of something, and it does not require much insight to recognize when we are doing this, and why we do so blinker ourselves. As Tajfel and many others have argued in the case of social categories, being able to reduce a welter of information to a manageable size has attractions even if we know that the basis of that reduction is flawed. Most of us prefer to develop a basis for action, rather than simply to contemplate the many-splendoured diversity of the world around us. Rushing fools may often make mistakes, but the virtues of angelic caution are not very appealing to most. — Diego Gambetta, Trust - Making and Breaking Cooperative…, 635

Categorization

• XREF: The drive to reduce information into workable categories connects directly to the reader’s Luhmann framing: familiarity/freedom from doubt as an economizing preference for knowledge