And you've never once hit upon a scenario where a backlit snap of some friends would not have turned out better with a touch of fill flash?? Never came upon, totally unexpectedly some animal at night on the way back?
I've certainly run across backlit situations needing fill flash...and I had a Speedlite with me. An animal at night...what, a house cat? Or maybe you think a popup flash would be useful with my 600/4? Or maybe a nice, close deer...really driving home my point about the 'deer in the headlights' look that sends the file straight to the trash can...except I wouldn't have even bothered taking the shot with direct onboard flash in darkness, popup or Speedlite.
This is not the final pose, angle, aperture or anything, which I can't post, but the test shot for emergency pop-up fill. Without the fill all the faces were shadowed and dark and not at all balanced to the background.
As I said, failing to plan is planning to fail. Nice that the popup flash may have saved you, but if you needed saving it was due to a lack of proper preparation.