Some DJ's are definitly musiscians. Your mainstream club dj that mixes one record straight into the other record, no not a musiscian. However if you have DJ's how are very good with turntablism, people like Kid Koala, Q-Bert, Invisibl Skratch Piklz etc. they are as much as a musiscian as your average drummer is. For those people there instrument is there set of SL1200's and they can create 'new' music from scratch. Yes i know they use other people's music as theu basis but it is something completely different then the original recording.
So tell me why a turntablist is not a musiscian?