Trump won the election because he won Wisconsin by 0.8%, Pennsylvania by 0.7%, and Michigan by 0.2%.
Black voter turnout declined 19% in Wisconsin from 2012 to 2016. That decline is 1.3% of the total voter turnout, larger than the 0.8% gap.
Pennsylvania is 11% Black. So there even a 7-8% decline in Black turnout could have made the difference.
Michigan is 14% Black. So even a 2% shift in Black voter turnout could have made the difference there.
Black people can certainly shift elections in purple states like Wisconsin, Michigan, and Pennsylvania. Make or break Florida too with 16%, plus North Carolina, Ohio, Nevada, and even Minnesota. Black people are what are holding Virgina in the blue column right now. If Black turnout was huge in Georgia with 31% of the population there that state could flip too. Even in a deep red state like Alabama the Black turnout was enough to make the difference in the last Senate election.
Just counting Wisconsin, Michigan, Pennsylvania, Florida, North Carolina, Ohio, Nevada, Minnesota, Virginia, and Georgia, that's 153 electoral votes in purple states that could be swayed one way or the other by Black voters. That's more than half of what a presidential candidate needs to win.
You could also make arguments that D.C., New Jersey, Maryland, Illinois, Delaware, and Colorado are getting held as strong blue states in part by Black voters right now. Or that if there was ever a blue wave in Indiana, Missouri, Mississippi, or Louisiana, Black voters would be a big part of it.
It's defeatist to say that Black people can't make a difference at the polls. There are a lot of states where Black people do make a difference. The vote just has to be used effectively.