I don't think that's true. Perhaps in your dialect of English, but if I was down the pub and someone started with, "Did I ever tell you the story of when I...", I certainly wouldn't assume it was fictional.
I think "tell you the story of" has a different connotation from "storytelling"!
E.g. if you said someone was good at "storytelling" as a skill, then I would expect it to be most likely fictional. I agree that "tell you the story of..." could easily be nonfictional.
I think "tell you the story of" has a different connotation from "storytelling"!
E.g. if you said someone was good at "storytelling" as a skill, then I would expect it to be most likely fictional. I agree that "tell you the story of..." could easily be nonfictional.