That is exactly how the Conspiracy writer gurus do it. They pick some small bits and pieces of the truth to blend it into the rest of the Conspiracy hogwash, to make it more 'believable' on a gut/intuitive level. Most people then can feel comfortable buying into the Conspiracy because it kinda feels 'right' and they don't have to bother thinking about what is 'right' any more.
It has all been figured out for them, and all they have to do is swallow it hook line and sinker and buy the rest of the conspiracy writer's books, because he is an artist at weaving, bending and spinning tiny bits of truth to fit his stories just enough to make it look believable to those gullible enough to believe and fatten the author's bank account.
Conspiracies are more exciting to read than the truth, and everything is already explained to the reader of the conspiracy exactly how every conspiracy is true. So the thinking has already been done for the reader.
And the readers know the truth because the conspiracy names an ancient extinct group or any group or club that has secrets for members only.
Now all the reader has to do is copy and paste excerpts to convince and warn others of their thruth.