Apparently the rite of initiation was a combination of the ordinance of baptism and the endowment ceremony. Initially, from what we find in scripture and in early Christian texts, baptism was a single, simple rite that was performed in public. But, in later centuries baptism was combined with another rite (the endowment) and because a private initiation rite.
Striking similarities. Would you suppose that these early christians received these “initiation ceremonies” through revelation as part of an eternal gospel or that they were guilty of adding pomp and circumstance to the simple and pure rite of baptism?
Either is possible depending upon your perspective.
Possible, but extremely unlikely, to the point of being impossible for all intents and purposes. The odds are fantastically remote that Joseph Smith et al would invent a ceremony that by sheer chance contained numerous specific parallels with ancient Christian initiation rites that were merely manmade expansions on the rite of baptism.