1. SCP is not, nor has it ever, been based in any VS conventions. You are unbelievably ignorant if you believe that to be the case. The SCP writers guild as a whole even made a formal announcement after SCP was removed from this site stating that there was never any use of Battleboarding ideals in the SCP community, with an
informal discussion that came before that announcement which was equal parts mocking and shaming this community for even thinking that it had any sort of influence over their writing as well as being genuinely shocked at the audacity of claiming to have created numerous concepts and ideas that have existed in the writing and scientific fields before battleboarding was even a thing.
2. I dont think you know what the definition of 'fanfiction' is. SCP is its own narrative, its own work of fiction. Saying that SCP is fanfiction of itself implies that any lengthy work of fiction is just fanfiction of itself. Marvel and DC is stupidly long and has a ton of writers, is it fanfiction too?