From Wiki -
"DMC World DJ Championships is an annual
DJ competition hosted by
Disco Mix Club (DMC) which began in 1985.
DMC’s World
DJ Championships, sponsored internationally by
Technics and
Ortofon, has grown over the years and the formats of its competitions have developed along with demand. Originally intended to be a DJ mixing battle,
DJ Cheese introduced scratching in his routine in 1986, changing the course of future DMC battles.*
The DJs are allowed a period of exactly six minutes to perform."
*and IMHO, not changing it in a good way. Scratching has it's place - just look at the transitions Chris did in his first "Virus Video" of 70's music. In general, that stuff is hard to mix, and scratching can help, especially with transitioning to a very different BPM. However, like all things,
just because you can do something doesn't mean you should. I personally have no use for scratching
as an entity unto itself, regardless of how good you are at it.
But hey, that's me - I can assure you the manufacturers of the $2000 plus mixers, that are generally used for this, absolutely LOVE it.