Many of the films mentioned in the OP were great of films..Daughters of the Dust, Just Another Girl on the IRT, Straight Out of Brooklyn etc. I know how Julie Dash was out casted by Hollywood because I learned about her in one of my Black film classes in undergrad. She wouldn't conform and write/direct movies using the seven stereotypical Black archetypes (The Mammy, the buck, the c00n, tragic mulatto, jezebel, sapphire and the brute). Every Black film financed in Hollywood must contain these archetypes. If not, your film will not see the light of day. That's why Julie Dash was shunned.
MARTIN And you had to do what they wanted you to do, too, because you were their black filmmaker. It was like, “This is the film, you’ve got to do it.” It was like, “I’m not feeling it.” but you had to do it.
This quote could possibly explain that awful Harriet Tubman and Madame CJ Walker biopic scripts. The outright lies (Bigger Long, Harriet/Master love story, Harriet walking to freedom, CJ's fictional "lesbian" daughter, CJ story turned into a colorism story) were written in the film and everyone went along with it for financial and workability reasons. On the flip side, it still makes you a sell out for going along anyway.