Well, 'avoid pure black' is as good a rule for design, as 'limit/compress your audio' is for music production. Both rules produce more 'polished' results, but both are kind of cheesy. Most professional audio engineers claim to prefer greater dynamics (though its rare outside classical recordings). Most professional photographers prefer glossy paper because you get deeper blacks (and whiter whites). I know that may strike some nerds as odd (matte displays prevent glare), but there is also a pro market for HDR displays, and 'true black' TVs/monitors.