Thread:Hanten'in-san/@comment-32173693-20170616164723/@comment-26709288-20170616213050

Maybe because Astarothfan and Houki don't want 100 pages of Naruto as Jesus Christ or Trihexa in the wikia. Astarothfan originally wanted to establish a rule that you couldn't create anything that deviated from source material meaning no new Gods, dragon emperors, nobody could have a sacred gear that a character in canon had, etc. But Bamefelix opposed it and therefore he changed his mind. The fact that they allow people to completely contradict established rules and lore in canon completley is enough in my opinion.

If no crossovers is a problem then why not just create a seperate wikia for it and simply link it to your work in this wikia so you wouldn't be breaking the rules while you can also combine your work? Or if you don't want to go through the trouble of making a seperate wikia you could use a site that doesn't have a crossover rule (like powerlisting where they allow anyone to make characters, etc.) and link your articles from there, here.

Just some ideas you could use.