The name itself is ironic since you can use a colour palette that isn't in black or white, that's allowed! Literally it says in the rules that any two pair of colours are allowed and they banned the very elegant greyscaling which constitutes 256 shades.
I would've been interested if greyscaling was on the table because it's hard to make a good looking game with only 2 colours of just solid white + black or any other pair TBH.