The TL;DW version is: "Look at what happens in failed states. When you purge competent people from the economy or bar them from doing economically efficient labor, you get abandoned hospitals, barren farms, unproductive factories, a power grid that can't reliably keep the lights on, and it happens in less than a generation."

All it takes is a little familiarity with Rhodesia and South Africa to understand just how fast running off all the people at the head of the Pareto distribution and giving their positions to people from the tail leads to complete collapse.