Exactly how that may have played out in the last century could be explained by many, many chains of causes and effects. But it wasn't a great leader that made it happen. At the bottom of everything, I believe it was this:

Decades of Famine, Pestilence, War, and Death destroyed not only capital but huge swaths of the labor pool. With labor at a premium, it became more valuable and power shifted.

I think that without a similar apocalypse, it will not happen again.

Yes, economic disaster is the driver (tangential: a lump-of-labor supply shock was not the transmission mechanism), but big political movements always happen from the pieces lying around. Everyone can feel that a disaster of one form or another is coming. We need to make sure the right pieces are lying around.