why did the Greeks learn of, say the story of Atlantis from ancient Egyptian tradition? “
Ha, consider that Solon visited Egypt but learned nothing about Atlantis! Didn’t Herodotus mention Solon’s trip, did Herodotus mention Atlantis? I suggest that Plato created a myth of Atlantis. A very realistic myth of Atlantis but still a myth.
That the story gets people interested in the ancient world is a good thing. IMO, it is still a myth.