thats the dem bench ex harris/booker. none of them can win over southern blacks over a black candidate.
That's a reasonable assumption about Harris and Booker with regards to the black vote. But the other candidates don't necessarily need to win the black vote; they just need to not be destroyed like Sanders was.
Blacks block vote.
Obama destroyed Clinton, who in turn destroyed Sanders.
No one on that bench, except for maybe Kaine, really has any connection to the black community. And blacks, especially southern blacks are becoming a greater voting block within D primaries for POTUS.
Klobuchar and Gillibrand don't have the cultural memory of HRC (due to her time in the south) to connect with this influential bloc. None on that list really do. Can you imagine those two, for example, campaigning in the south?