It's not even always relevant in painting. The impressionists (who invented the hatred of black, AFAIK) were obsessed with painting light effects, so to them it

It's not even always relevant in painting. The impressionists (who invented the hatred of black, AFAIK) were obsessed with painting light effects, so to them it was important. Their academic colleagues and to the painters that preceded them didn't care about photorealism and so used black liberally to emphasize depth and contrast.