Not QUITE the truth; it's more like the Doom Wiki originally started on Wikia, so it was indeed written originally by members of the community. But they eventually got fed up with Wikia's eventual evolution into an ad-plasterer, and so one day, they backed up the content and split cleanly off from it. There's no mechanism for deleting the content they had there (and would already be out there on mirrors and the like, anyway), so about all they could do to protest the direction was to, very literally, disown it and disassociate.