I think Sanger has conflated multiple streams of argument here.
The first is marxist and postmodernist critiques of the classics. "Dead White Men" and all that jazz.
The second is the demoticism (not the democratisation) of the internet.
These are unrelated, in my view. The PoMx/PoMo criticism is more political, in my view, than what it purports to critique. The change in demoticism is itself not a fundamental change but a rhyming riff on what has happened in the past.
Today the classics have never been more accessible. But just as when Penguin Classics was introduced, most people want penny dreadfuls, potboilers, comic books and a generous helping of porn.