I spell it out with examples in another comment here, but one shouldn't assume that everyone has equal access to the foundation and motivation needed to put out the "effort" to succeed in MOOCs.
The people who are really educationally disadvantaged are often that way because of some other difficult circumstances in their lives (violence, social breakdown, poor parenting, and the associated effects on motivation).
I'm not referring to (typical) hacker news types here (myself included). You could give us all the extra educational access in the world and you wouldn't make a dent in educational inequalities, whether in the US, or globally.