I totally not believe this story as a reason why reliogisity (and the tendency to "believe in things and experts) has established.
I think it is much more plausible that people who believed in some higher forces had less doubts, had more comfort in their daily worries, had a kind of reason to accept their fate, and on the other side there were special people who confirmed those religious beliefs to the normal people. Call them shamans, priests, medicine men, whatever. Tribes with such a specialization in 2 casts - believers and people who confirmed the beliefs - were overall more easy controllable and thus more successful compared to tribes who had no clear vision or were doubtful on this and that. This evolutionay advantage led to the today pattern which might be even genomically imprinted or what you call as "inevitable".
BTW: Not all kids have imaginary friends, so to use this with regards to religion seems quite far-fetched.