Many 'microwave' DJs insist that being a DJ is not about the 'traditional' skills, but ONLY about the ability to 'rock the crowd' -- "it is not what you do, or know how to do, but the end product".
The Milli Vanilli analogy confronts this belief, as it infers that there is an ultimate element to reproduction that makes implicit what is portrayed in that reproduction. A DJ receives his acclaim due in part to the implied contextual idioms that are synonymous with being 'a DJ' -- the traditional song manipulation skills.
A ‘Milli Vanilli DJ’ is one that relies heavily on software to 'rock the crowd' without publicly acknowledging that this is the case. But, as it happened to Milli Vanilli:
"In 1990, during a 'live' performance recorded by MTV at the Lake Compounce theme park in Connecticut, the recording of the song "Girl You Know It's True" jammed and began to skip, repeating the line "Girl You Know It's-" over and over, resulting in one of the most embarrassing moments in popular music history." (taken from Wikipedia)
If the Milli Vanilli DJ’s software freezes, or he forgets his USB cable, control vinyl, or laptop this creates a unique problem for that DJ. If the promoter or anyone else (very likely to be another DJ on the card that night) has regular turntable decks and a slew of popular vinyl (vinyl that the software DJ should already be familiar with), this particular software dependent DJ cannot recover and/or perform under these circumstances -- where he/she would at least be expected to.