Absolutely nobody is assuming that everyone is prescient about the future, nor even that they are perfectly informed about the present let alone the future.
There have been a lot of changes in the digital world recently, which is a perfectly accurate observation but fails to present the full scale of the transformation.
Hours of new content, a new multiplayer arena, a fleshing out of the lore and history of the fall of Lordran, all perfectly tied into content and story that was already present.
The length of the reference path is such that if no sample is present, the two daughter beams will be as perfectly in phase when they meet as they were when they were separated.