Complex societies collapse because of the complexity. And that’s that.
Complex societies do not encourage nor reward pursuit of self-sufficiency in sufficient numbers to perpetual such societies in the event of cataclysm or severe destruction resulting from war. Any given individual is far more likely to have specialized down to such degree as to be largely nonfunctional outside the confines of the complexity that exists no longer.
True.
As Henlein said, specialization is for insects.