Here is the issue. At maximum levels with too much compression , most of your audio will be between 16 and 12 bits so lets say average of 14 bits, and that’s probably generous for most types of music. At full 16 bit, the numbers pan out. But you are rarely hitting a full 16 bit signal. Your average is probably closer to 10 bits.
on a 24 bit signal, you ar getting a consistently higher resolution on average, most likely 16 bit an above for a good part of the signal.