The use of a "writers bible" will help keep your thoughts organized AND if your product is successful then you will have a structured document to use when hiring out to further develop your product. 've tried to work with a publisher that has two decades of publishing but no source material for writers. The expectation is that the free lancer will have bought and read all of their products to stay up to date with the setting. 20+ years of adventures and splat books is an unreasonable ask. Of course, that's only if you're solicitating submissions.