Here's the key part of your quote, that you failed to grasp:
That IS the way to prevent income disparity. When the "rungs" are further apart, social mobility is more difficult.
Every time I hear an idiot bitch about income disparity it's always from someone who's never accomplished a damn thing in their lives. They're wired for failure and lack the emotional intelligence and intellectual honestly to take a hard look at themselves in the mirror and admit they're responsible for their own actions and the choices they've made.
They're cowards.