Enlightenment, like any other belief system that gains worldwide ascendancy for a time, is really just a tool. The fact that its thinking came to dominate an entire age can be explained by its usefulness for those seeking to challenge entrenched power structures and hierarchies. In any age, those lacking power and resources consistently outnumber those who possess them, and when belief systems (and corresponding movements) emerge, promising retribution or redistribution for the dispossessed (or less privileged), who are inherently more numerous, they tend to rapidly proliferate. The thicker the forest, the quicker fire spreads and burns!
Not truth, but utility ultimately determines which beliefs become banners and rallying cries. Certainly, it is usually the case that beliefs that appear to be true are more attractive rallying cries and, thus, more useful. However, this is not always the case.
In the early days of the Enlightenment era, was there ever really any chance for hereditary succession, for instance, to be declared compatible with "reason"? Was it merely the luck of the draw that the canonized precepts of the Enlightenment consistently worked to diminish the power of kings and hereditary nobility?
Enlightenment served as a convenient ideology for those who yearned for elite status but lacked it, as they sought to displace what they perceived as unworthy elites. It is precisely because their adversaries could be categorized as unreasonable that reason became the rallying cry.
However, had this entrenched elite enjoyed "reasonable" privileges, unreason would swiftly have become the rallying cry for the ambitious but disempowered. In such an alternative scenario, the principles of unreason and absurdity would be ripe to be sanctified. Claims would be made that everything is unjust until the will of unreason spreads even to the highest echelons.
If the powerful today seem to be descending upon a path contrary to reason, it is only because they believe it to be advantageous to discard reason. The absurdities preached in prominent political circles today do not demonstrate weakness as much as they confirm that elite strength has deemed it necessary to adopt a different language, one that is no longer reasonable.
What was once a cherished tool that helped them attain their current status is now better cast aside, preventing the dispossessed they have left in their wake from learning the lessons of the entire Enlightenment era and using these lessons against this new elite in turn. What once aided them in overthrowing the monarchs of the past now poses a threat to the latest elite's newly entrenched power. How swiftly and thoroughly even the most natural alliances can crumble during critical moments of any succession crisis! Power always takes precedence over consistency. The Enlightenment fulfilled its purpose, and today's elite have begun to sever ties with it – first in practice and, finally, one day, fully in name too.