"The psychiatric establishment classes DID as a mental disorder, and denies the possibility of any other sort of multiplicity."
Actually, no, it doesn't deny the possibility at all. It may be skeptical about the exsitence of such a condition, but I think saying that they deny any possibility is being just a little extreme.

"The fact that the psychiatric establishment is an instrument of repressive social control with a long history of perpetrating atrocities against the innocent..."
Uh. Conspiracy theorist? Over the top, for sure.