That's the noise floor, which should be below the threshold of human hearing unless you turn the volume up so high that the loudest signals would be uncomfortably/damagingly loud. 16-bit digital audio has a dynamic range of 96 dB. Even in an extremely well-insulated anechoic chamber where we (unrealistically) assume the ambient noise level is 0 db, you would theoretically hear extremely quiet white noise when playing back a plain old 16-bit CD, but that CD would still be able to blast out 96 dB which in nearly all imaginable circumstances would be louder than desired. In a more realistic scenario wearing well-isolating headphones in a very quiet normal room, the ambient noise level is probably more like 30 dB, and plain old 16-bit audio gives you plenty of dynamic range to perfect reproduce any conceivable digital audio signal for the vast majority of use cases. Certainly for things like music, I think it would be quite rare for a recording to have a dynamic range greater than, say, 60-70 dB.

Dither works for images too, e.g. for cheap displays that only have 5 bits of color depth. It's hardly a problem for audio anymore which is now almost universally 24 bits (and arguably already wasn't an issue at 16..).