Without the "Obama factor" and not counting Hillary's cold shrill white-lady negatives within the black demographic, the fact that the Federal Government seems to be more interested in helping import new Latino immigrants, legal or otherwise, than helping out black communities probably did help suppress their vote in 2016.
And in part, it's true. Because at least a large portion of these immigrants are willing to work. And that's what creates the unholy political illegal imigration alliance, the Democrats who want the votes, and Republicans being pressured by business desperate for the labor.
And of course, even if the poor black U.S. citizens were willing to take the jobs that the Latinos fill, legally or otherwise, 50 years of LBJ's "Great Society" has left far too many blacks unable to fill those jobs due to temperament, work ethic, or experience.