If neutrality is impossible, as certainly seems the case; and if humans are simple creatures capable only of dichotomous evaluations (as certainly seems the case) - then it is both futile and dangerous to regard prejudice as 'a bad thing'.
Futile because prejudice is inevitable, a bad thing because in attempting the impossible task of eradicating the inevitable, prejudice is not eliminated but inverted.
So we find that a Leftism which affects to be eliminating 'prejudice' has merely inverted prejudice; and to the extent that traditional prejudices were broadly valid (true for most aspects of most of the people most of the time, as a general rule), Leftist prejudices are broadly invalid (true only for exceptional individuals under exceptional circumstances).
So if prejudice is inevitable, and if the alternative to prejudice is evil - then prejudice is good.
Yet of course we all know (because our culture continuously points this out, and continuously depicts it fictionally) that prejudice is often mistaken and may serve as a basis (or excuse) for evil.
Then the obvious conclusion, which all wise and decent people have spontaneously reached in the past, is to accept traditional prejudices but be prepared to revise them in specific instances in the light of further knowledge.
Prejudice plus feedback equals wisdom.
Really, this isn't rocket science!
We regard the average 8 year old child as less intelligent than the average adult, and this prejudice is usually correct; but should be prepared to revise our evaluation on the basis of further knowledge that this specific child may be more intelligent than the average adult.
We regard as dangerous a young man with a fierce face running at us wielding a weapon (and act accordingly); but should (after taking the necessary action) be prepared to revise our evaluation on the basis of further knowledge that this specific knife-wielding youth is a member of an ancient warfare re-enactment society with a blunt weapon about to join a choreographed battle behind us (which we hadn't noticed).
And so on.
Is that really so difficult?
Then why all this evil nonsense about eliminating prejudice?
A: The evil nonsense is an accidental by-product of extreme stupidity, inability to follow a very simple and obvious line of reasoning?
(i.e. Primarily nonsense, accidentally evil.)
B: The evil nonsense is an elaborate form of rational selfishness by which elite Leftists feather their own nests.
(i.e. Primarily evil, but not nonsense.)
C: The evil nonsense is a product of evil purpose+.
(i.e. Primarily both evil and nonsensical - the lack of sense itself being a part of the evil.)
+Note: Further elucidation requires an understanding of the origin and nature of evil in the world.