Critically, the benefits of audio dithering come with a single side-effect (i.e. audible artefact): an increase in the noise floor. In most cases, however, this elevated noise floor remains below the threshold of audibility, or more practically, quieter than the ambient noise of any reasonable listener’s playback environment.
What's important to appreciate is that dithering digital audio should only ever be performed when preparing a final export for distribution, and even then, only for bit-perfect copies. You shouldn't dither when the next step is a lossy codec. Encoders for AAC and Opus accept high bit depth originals, because their encoded files don't have a native "bit depth". They generate and quantise (compress) MDCT coefficients. When these encoded files are decoded to 16-bit PCM during playback, the codec injects "masking noise" which serves a similar function to dither.
What's important to appreciate is that dithering digital audio should only ever be performed when preparing a final export for distribution, and even then, only for bit-perfect copies. You shouldn't dither when the next step is a lossy codec. Encoders for AAC and Opus accept high bit depth originals, because their encoded files don't have a native "bit depth". They generate and quantise (compress) MDCT coefficients. When these encoded files are decoded to 16-bit PCM during playback, the codec injects "masking noise" which serves a similar function to dither.