What is the consequence of assuming the opposite? E.g. IQ has very little effect. You can use that assumption as cover for garbage social policy that doesn't

What is the consequence of assuming the opposite? E.g. IQ has very little effect. You can use that assumption as cover for garbage social policy that doesn't recognize individual differences in intelligence and attempts to equalize outcomes when the distribution in ability is inherently unequal and leaves everyone less happy. What I believe is that the interplay MAY be complex, but your argument that an unqualified assumption leads to bad outcomes works both ways.