It totally isn’t, and I can point you to at least 20 years of history of it not being. 

Frankly I find the insistence that DID is the only way to be multiple as laughable in part because the psychological institution *hardly even recognizes* DID as being a real thing. Like there are legitimately a lot of psychiatric professionals out there who outright don’t believe multiples exist at ALL and think we’re all faking fakers who fake.