What if you're designing for OLED panels, where black is a stand in for "pixel off", which saves power and can help to hide bezels or (as with the default iPhon

What if you're designing for OLED panels, where black is a stand in for "pixel off", which saves power and can help to hide bezels or (as with the default iPhone X Wallpapers) a notch. Sure, it's not trivial to get right, and it should definitely not be used outside backgrounds, but never is a harsh word.