Probably important to remember that like everything else in the world Egyptian religion evolved ( bad news there, Waldork!).
We do not find any religious texts until the pyramid of last king of the 5th Dynasty, Unas. In spite of what the Egyptologists claim therefore, all of the prior pharaohs of Egypt, including Djoser, Sneferu, Khufu, Khafre, and Menkaure did not seem to have any magical incantations guiding them to the "afterlife."
So when this idea popped into Egyptian consciousness is open to speculation but it seems very odd that the majority of the Old Kingdom did not act on it.
We do not find any religious texts until the pyramid of last king of the 5th Dynasty, Unas. In spite of what the Egyptologists claim therefore, all of the prior pharaohs of Egypt, including Djoser, Sneferu, Khufu, Khafre, and Menkaure did not seem to have any magical incantations guiding them to the "afterlife."
So when this idea popped into Egyptian consciousness is open to speculation but it seems very odd that the majority of the Old Kingdom did not act on it.