Why historical context matters.
White men overpowered black men, calling them the N word before stringing them up or burning down their neighborhoods. When a black man heard the word, it was reason to fear for his life. The murders and tortures were brutal. The damage done to black enterprise, community, and family cannot be understated.
There is nothing even close to that context when cracker is used. And cracker isn't a derogatory word, it's a reminder of the physical dominance of whites over blacks over the centuries.
If anything, cracker is anti-racist. Racism requires an element of superiority of one race over others or inferiority of one race compared to others. I don't see the superiority/inferiority (blacks saying whites are inferior) in cracker.
FWIW