The above is with respect to young black females not black actors and actresses as a whole. It even points out that there are dark skinned black actors like Elba, Boyega and Moore that don't have a problem.
Further this ignores the whole host of older black actresses like Basset, Davis and even Lupita.
Zendaya or Shipp have not reached the level of success that those women have.
So you are taking a very narrowly defined problem relates to young black women and incorrectly applying it to black people as a whole.
http://www.imdb.com/list/ls003135959/
None of the young black females mentioned appear on this list because the actual top dogs in the black acting world are still dark skinned black people.
If you want to limit your argument to just young black females then I am inclined agree. However applying it to black representation as a whole is not supported by the facts. There are plenty of top dark skinned black actresses and actors and it remains to be seen if any of these light skinned younger black females really make a dent on the big screen.