it's a lie
It's just a repug lie to divert our attention from the banksters so we can hate our own government - mostly fueled by Southerners who still want to win the civil war and bust the union.
Even if the govt relaxed lending requirments, they did Not dream up this idea of slicing and dicing mortgages into worthless instruments, then selling and reselling them all over the planet, inflating their value a thousand time - which is what caused the Real damage. The banks thought that up all on their own.