DID is one of the ways to be plural. DID is a form of traumagenic plurality, which means the system was created by trauma. The other big category is endogenic plurality, which is when the system is created from within.

There’s actually a significant faction of systems with DID and OSDD who think that traumagenic plurality is the only genuine kind of plurality. They think endogenic systems are all faking it. That view is called sysmedicalism, because they think your system is only real if you’ve been diagnosed by the medical industry. The debate between sysmedicalists and endogenic allies is called syscourse.