If you can customize the display based on the user's device, then we are back to the current problem of companies not customizing the display based on the user's device.

My understanding is people want a format that machines and computers can read without introducing a translation layer.

>the alpha portion can be localized

but can it? if you're putting dates in something like filenames or CSVs, then no, it can't be localized. you get one string, and that's it. if you're displaying a date in an app, then whatever platform you're targeting probably has some method to diplsay a localized date, and you should use it. but for anywhere that you have to choose a date format, that probably means you don't get to localize.