From my personal experience, people who are successful usually come from highly educated and/or wealthy families. I don't think school plays that much of a role in the grand scheme of things compared to family influences. There's a lot of inertia to society in general.
However, what we lost is that modern educational systems are really bad at identifying and "pulling up" talented kids from poor / under-educated families, because the standards and expectations are so low that you can't differentiate them from their peers.