The argument for mainstream 24bit dynamic range shouldn't be for higher fidelity reproduction for audiophiles. It should be for enabling more sophistication in our playback devices. In the YouTube era not every recording is perfectly mastered by audio engineers to fill the available range. And I could be listening on high end home theater equipment or the tiny speaker in my smart phone.
What about 24 bit enables "more sophistication in our playback devices". Doesn't sufficiently high fidelity mean you can already listen on your high end equipment?
It would allow our playback devices to correct poor quality source material without introducing distortions or clipping. All the same reasons why 24bit is preferred in the studio. Basically studio-quality post processing would be possible on any mainstream content resulting in higher fidelity ultimately. Also, if you consider mashup style content where people are producing derivatives based on already mastered material it would generally increase the quality of that material.
