For one, we can use the truth to defend ourselves against claims that white people are the root cause of hardship to blacks. Embracing the truth means we're not to blame for these people being congenital life failures, and anyone who says otherwise can fuck off. On the other hand, if you accept the lie that we're all equally capable, prepare to forever be on the defensive about why some groups are more successful than others because you just legitimized the core Marxist theory that society is nothing but an oppression hierarchy and deserves to be knocked down. Long story short, lying is bad.