" Argument: Don't use black because nothing in nature is actually black.

False Conclusion: Don't use black on a web page because nothing in nature is actually black.

False Assumption: The black on a web page is actually pure black.

True Conclusion: Use black if you want to - it won't be pure black, it will simply be the darkest you can get.

PS. This is also true for paint: Black paint is also not pure black. " -ars https://news.ycombinator.com/item?id=6581935

Kinda unrelated story: I ran into trouble using "true black" (A combo of CMYK) on a van wrap. In all the testing I did, it looked fine, but outdoors, it looked green. But photos of the wrap looked fine. (the camera has a uv filter?) Figured out that the cyan ink fluorescenced in daylight with that combo of ink and material at least. And converted it to just black ink for the next ones.