Regarding your reply, there are two things to address. First is that of economic mobility, which I referenced casually with "meritocratic sentiment." I'm not ready to say anything conclusive, but as other posters have pointed out, there is reason to disbelieve the popular belief.
In the very page you link to: "While there is some economic mobility between generations in the United States, it is still difficult to move up one or more quintiles in regard to one’s income."
But again, I am not one to make conclusions about this topic; I merely express skepticism and disagree with those who hold strong opinions one way or another, because either borders on irrational conviction.
The second point, which you don't address, is the effect of generational wealth on offspring. The effect is subtle and easy to overlook, but is as important as wealth itself. Why do the rich stay rich, and the poor stay poor? It's not as simple as saying the system is or isn't in favor of mobility. You must also consider the possibility that rich offspring have become inherently stronger, smarter, and prettier than the poor -- and they are. There has been research on this topic, but it is intuitively obvious: a desperate person is not attractive, is brash, and is weaker against temptation.
The symptom is one: wealth disparity is increasing; but the disease is manyfold. That's my "theory". The problem here, is that somebody will write an article illuminating one facet of the problem, just like somebody takes a magnifying glass to examine a rash. Then somebody reads it and says, "let's apply Cortisone!" But it's actually an allergic reaction to an ingested substance.
The skin-deep understanding of society helps perpetuate this "credit hog" mentality. And that in my opinion is among the foremost barriers to equity.