Each article itemizes a list of major empires whose collapse was due to the withdrawal of externally supplied energy caused by severe draught. That is because their size and complexity allows them to save up food and water internally to go without for a while. But a bacteium in a desert or a spider frozen in winter needs only comparatively minor amounts of energy to reproduce abundantly. Hence, over the much longer term, a prolonged draught will kill all of the elephants because any sporadic intermediate rain will not be enough to keep them alive. However, only a few tiny sprinkles will be enough to allow the smallest life-forms to quickly reproduce that a few might survive to the next sprinkle.
History teaches the same social lessons for the same reasons.
Big complicated societies require large volumes of energy that is sustained and reliable. Temporary shortages can be endured, but prolonged cut-offs cannot be survived without contraction or collapse. Human societies grow in population and complexity to the limit of their energy supply. Once at that limit, system stability becomes precarious and breakdowns more frequent, insofar as the core energy supply may fluctuate due to external forces. When and as our OWN global system collapses various social movements led by charismatic individuals will doubtless claim credit in various places and triumphantly announce the dawn of some new era, but their effective control will be limited by the energy available to them at that moment, which by definition will be declining into micro-fiefdoms.