I feel like [1] hints at the reason: > Finally, the digital effects used in studios to mix music benefit from the higher 24-bit resolution file for microscopic

I feel like [1] hints at the reason: > Finally, the digital effects used in studios to mix music benefit from the higher 24-bit resolution file for microscopic processing duties. Using 24-bit over 16-bit keeps the door open to any post-processing the user wants to do (e.g. restoration/enhancement). I very much doubt that they consider it necessary, or even useful, for general listening.