But the author of that page is not concerned with readability or accessibility. He just wants things to look cool and design-y. One piece of supporting evidence he cites is some random photo he took that doesn't contain #000000 black. That doesn't mean anything, it could be that it's over-exposed, or has poor contrast, or had some silly filter applied. This leads me to think that the author of that page doesn't know what he's talking about.