HDR post-processing is not being used to standardize the color subsampling accuracy of digital video files. It is being used to coerce pixels to following one particular subset of high-gamut color curvatures. It is NOT the same thing as 10bit color, nor as wide-gamut color spaces. It is a post-production trick used to make your eyes more enticed by the picture.
It is not about higher fidelity picture, it is about higher engagement viewers.
Still, I don't think HDR is a net negative even if its just improvements in luminance -- LCD TVs are especially bad at representing shadows and I have grown tired of watching thousand-dollar TVs treat dark images like a cheap laptop. Was hoping HDR would do something about that :/
Bit depth will give you a value per color channel between zero (black) and the upper bound for that bit depth (2^n - white). How the image data is encoded in those values is very much standardized for all display colourspaces (though whether the hardware is capable of displaying the full range of those values correctly is a different story).
HDR is certainly not a fad - the current crop of displays are nowhere close to being able to display the full potential of the technology yet (100% of Rec.2020 gamut @ 10,000 nits)
AndrewUnmuted - are you perhaps confusing 'true' HDR with upscaled / gamut mapped rec. 709 material? e.g. taking an existing rec. 709 master and mapping the color to a larger colourspace?
Netflix, Amazon and several other OTT providers have their original content mastered in true HDR from the get go - no post processing 'tricks'. The main limiting factor is the acquisition source, which is why Netflix have gone down the route of specifying acceptable cameras for use on their original content productions.
I don't know the technical details of HDR but this sort of curve compressions is a common trick for matching a medium to our perception. Unless important info is lost, who cares?
Or, can anyone present a head-to-head comparison between 10bpp+ or "HDR"?