[xyzzyz]

You could make the same point about the actual color “white”. You can point to various items of different colors and ask “is this thing actually white?”. You’ll have some people agreeing on most of these things, and disagree on some of these things. Would it make the whole concept of “color” meaningless and useless? Hardly.

[wruza]

You couldn’t, there’s no such contrast in any corner of colorspace to fit gp’s comment into.