As a keen amateur photographer, shooting with a Canon DSLR, I've never felt the need for 16 bit RGB.
It's interesting that the author talks about posterization at 8-bit, but demonstrates it with a 50-level gradation (i.e. less-than-6-bit). Why would someone do this?
He then add "Pundits that suggest this is negotiable are simply and flagrantly incorrect" -- a footnote that leads to absolute no supporting evidence of our incorrectness.
Yes, certain specialised applications need higher bit depths, and yes, the gamma correction in GIMP could be considerably better, but overall this article adds literally nothing to the debate. He doesn't show us the better results of higher bit applications, just repeats the same old talking points. (And of course, everything he writes about 8-bits-per-channel is true about 12-bits-per-channel, and he makes no effort to demonstrate "12 is good enough"). The Pantone system, quantizes everything onto about 3000 spot colours, but no-one talks about the quantization effects of that.