It is easy to blame the mustached one - but the reality is that I don't think the German high command expected the French to cave so easily either.

And once this kind of thing happens - much like the US going into Iraq twice - all sorts of nonsense thinking starts permeating both politicians and sycophantic military types.

So while I understand the viewpoint of reason you are putting forward - at the same time, it is exactly what I said: ex post facto. We now know far more than anyone, anywhere, on any side knew back then. There were no satellites or multi-generational scholarship much less records to look at.

But let's look at your other examples:

Manchuria - as I understand it, the Soviet steamrollered the entire Japanese mainland armies in about 2 months. The Japanese were already losing badly - this just put the final nail on the coffin. From a "reason" standpoint, it was delusional for Japan to attack the US to start with notwithstanding the ongoing McCollum memo provocations, but attack they did. Clearly "reason" was not the primary driver since even then, Yamamoto and many others knew full well just how overmatched Japan was against American economic might, manufacturing capability, population, wealth, literally any measure you can possibly think of.

The Finns: whatever victories the Finns won, the result would simply have been a depopulated Finland. And this was transparently obvious even to them. This isn't reason, this is sheer survival.

Whites: when exactly have sea powers been able to conquer land powers? It has never happened - not with the British against the Spanish, not with the British against Napoleon, not with the British against both rebel and independent ex-Colonies in North America. Only in places like India where the sea power could enlist local tribes against their rivals, could Britain succeed. And this situation was no different with the Whites against the Bolsheviks - notably that the Soviets in the Russian Civil War era were far more poorly organized, industrialized, etc as compared to Stalin's Soviet Union. Nonetheless, the sheer scale of supplying massive continental armies is just too much - it is 100% that the Allies could never have successfully penetrated France if the bulk of the German army wasn't on the Eastern Front getting smashed.

But this is a digression. The original point was simply that the French did not even slightly try to fight after their initial massive setback. Not only that, there was a Vichy collaborationist regime; the Germans didn't even have to work that hard to occupy France.

Reasonable? Perhaps so but also not in any way a mark of distinction. Would Germany have gone on to do all the things they did if they had a restive France being the other side in a Peninsular war? There is such a thing as being so fractious as to be unconquerable. The Afghans are notable for this among others.