African American turnout is as important to the democrat party as white male turnout is to the Republican Party. In high turnout elections suburban white women are the deciding demographic.
11 percent of black Obama voters stayed home in 2016.Black voter turnout was down eight points in 2016 from 2012.Obama had a 90% + black approval rating,Bidens black approval is around 60.
Add to that Stein getting a million more votes in 2016 than 2012 along with millions of white progressives staying home white women were not the deciding demographic.
I predict the black and progressive turnout drop from 2020 to 2024 will be far greater than the black and progressive turnout drop from 2012 to 2016 if Biden or another moderate is the nominee.