Of course, in this case, the logic is being applied to the audio stream as a whole, not just individual frequency bands. Since the voice activity detection is removing background noise, the lack of energy in the audio stream seems odd to the brain, so the noise has to be added to compensate.
The same seems to apply in dealing with images and video: the eye notices a lack of detail (blurring) more than it notices inaccurate detail.
... and now that we're on the topic of strange subjects involving telecommunications, I've managed to distract myself by listening to recordings of numbers stations again.
Besides what is listed in the article, prolonged silence may result in media platform forcing disconnection. For example, that's why special RFC exists for RTP for comfort noise. However, not all user agents (neither all platforms) honor this rfc. Note that I use the term "media platform" for any media gateway or media server, that establishes and manages connections between two or more clients.
The problem was that if they actually cut to black, that would trigger the commercial - the software that controlled when the commercials went on must have monitored the signal, and when the video was black, played the commercial reel. So they had to cut to almost-black to avoid ending the scene prematurely.