(To preface this, Emerald onwards. RS FRLG doesn't have the ability perk, hence I didn't mention it.)
Also this myth was likely caused by a misunderstanding from NPC dialogue in Lavaridge:
I would say the misunderstanding arose from the first half of that paragraph. Or maybe the idea was romanticized.
In any case, we gotta remember the NPC clearly says it is not enough, and gives the player the egg.