Aside from the Zuckerberg "young people are just smarter" quote, I suspect a lot of this is more side-effect of businesses (especially large ones) wanting inter

Aside from the Zuckerberg "young people are just smarter" quote, I suspect a lot of this is more side-effect of businesses (especially large ones) wanting interchangeable, easily-replaceable parts rather than overt ageism. Having a core business system done right the first time by an old-timer or two kind of puts you at their mercy. Using the infinite monkey theorem to grind out a bunch of python and javascript is much safer from a managerial perspective.