Because it’s a stereotype, it’s fervently believed by the Great and the Good that it absolutely can’t be true. That would mean that average people sometimes correctly notice patterns, and we can’t have people noticing things for themselves. It’s central to the dominant mindset that regular people can’t notice patterns. Whether “can’t” is used empirically or morally is left vague, with upholders of the conventional wisdom switching from one to the other.
I have a longstanding aversion to non-associative thinking. I want to daisy-chain everything together into giant hyperlinked multidimensional arrays. That’s why I’ve always loved paranoid literature and random newsbits: not because I believe them necessarily, but because they make such pretty collages of semantic connections, sometimes poetic or pedantic, sometimes absurd, sometimes profoundly moving, and occasionally implying deeper meanings.
People who don’t do this naturally, or who do it but are not aware of it, or who throttle it through some kind of cultural filter, come up with little labels to dismiss associative connections, such as “stereotype”, “bias”, “racism”, “crazy”, etc. But everyone thinks this way whether they label it or not, and whether they categorize their findings or not. The problem is not that such an observation is biased, but that someone might believe it to be factual rather than interpretive. Even if it were factual, that would not make it true, especially if its truth were dependent on causality or some kind of statistical pattern.
It is supercilious to dismiss the observations of lesser-status minds as biased just because one is lacking in conviction and attachment; truly, the higher-status mind is just as biased even while it is floating free on the postmodern breeze. But its bias tends toward conspiratorial fantasies about socialist property confiscators, welfare cheaters, community organizers, thugz, and ugly homeless people. There is no social reward so deserved and fixed that a paranoid rich person cannot conceive of how to lose it swiftly, thrusting them into the depths of the seething masses who just can’t seem to game the system effectively.