Evidence of racism in the justice system is compelling. Things like the study in St. Louis that compared the stop rates, search rates, and arrest rates for blacks and whites, things like drug national drug usage rates for blacks and whites vs drug arrest rates for blacks and whites, and things like sentencing patterns for the same crime that differ based on race.
If you look at that evidence and believe it, it's hard to think that the entire justice system isn't racist. And if the entire justice system is racist, it seems likely that the same racism exists in things like education, employment, and housing.
And if essentially all of American society is racist, arguing that black people just need to work harder and be better parents is stupid and pointless. Yes, everyone would be better off if everyone worked harder and was a better parent, but blacks aren't inherently lazier than whites. Blacks aren't inherently worse parents than whites. The poverty and the issues with single parent households are just symptoms of a bigger problem.