The Moynihan report decrying the break down of black families was released in 1965, before the drug war, at a time when incarceration per crime committed was approaching all-time lows.
The incarceration rates in America bottomed out around 1973. At that time, about 63% of black and poor persons lived in a single-female headed household. By 1978, with incarceration rates still within their historical range, the rate was nearly 70% (source Losing Ground by Charles Murray). Family structure breakdown came first, it was not caused by incarceration. It is wishful thinking to believe that if all these men were not locked up they would be upstanding and faithful fathers, the problems go far beyond that.