[thaumasiotes]

> Occam's razor would dictate that the simplest explanation for an extremely fast rise in numbers of dispersed communities evangelizing the teachings of a person is that such person existed and espoused those teachings, right?

No? A large number of dispersed communities cannot have all been exposed to the hypothetical founder directly espousing their own teachings; the phenomenon you seek to explain actually precludes the explanation you're trying to give.

A rapid rise in dispersed groups following a set of teachings has to be explained by a large number of people espousing those teachings in parallel. It makes no difference whether those people got their knowledge as disciples of an individual person, as members of a committee devoted to a supernatural force, by reading the same book at the same time in different places, through the grapevine, or by independently adapting their teachings to what their audiences want.