Precisely. "Hypothetics tell us nothing".

All we can know is that the history we had, with the catastrophe of the Great War leading inexorably to the even greater catastrophe of World War II, and the agony that followed, which is still unfolding, was an awful history. And that, at the time the choices made that led to it seemed sensible enough.

And the lesson should be to look at what we do today, and be aware of the terrible and unwished for things that can come from what seem like sensible choices.

But there can never be any guarantee that the choices we make will be the best ones.