My Guess is that it is mostly a security through obscurity thing for now, we do not know exactly how they mark the audio. When someone figures this out I believe that it should be possible to filter this out.
It would be interesting if they found a way to watermark the audio in such a way that removing the mark makes the audio unusable.
It would be interesting if they found a way to watermark the audio in such a way that removing the mark makes the audio unusable.