Native speaker here, and that's the first time I've ever heard such a distinction. Nothing on Google seems to back it up either, so take the asshole's explanation with a grain of salt.
Most of the cleaning waves in the MMC happen at night while we are asleep. For many people this will be sufficient to help maintain a healthy, balanced environment in the digestive tract.
To be fair, that's exactly how economies of scale and market demand works. Given the preferences of most customers, it probably costs more to make it manual than electric today.