First, Upper-Class Chad uses MySpace. Later, he switches to Facebook, but he doesn't delete his account. His acquaintance Lower-Class Rodney is his friend on MySpace. Rodney worked as a line manager for a construction firm until getting laid off a few months ago. Rodney still only uses MySpace, because Chad didn't post on MySpace about Facebook. Chad links to all his upper-class friends on Facebook; many had never joined MySpace in the first place. If Rodney were on Facebook, he would occasionally interact with them, but he doesn't. He also doesn't see when Chad updates his Facebook status to say that his dad's company is looking for experienced line managers in their bill-collection firm.
That's the sense in which social stratification denies opportunities, whether it's manifested through YASNSs or other means.
But access to Facebook isn't denied to Rodney, and why would Chad not add him as a friend on Facebook, too?
I am also not friends with everyone on Facebook, so I guess a lot of opportunities are denied to me (because Chad doesn't tell me about the job offers either). It's a cruel world.
Wouldn't the most likely explanation simply be that the connections on social networks tend to mirror connections in real life? I think there was a study posted to HN recently that basically said instead of connecting to everyone and their dog, connections tend to stay local.
That's the sense in which social stratification denies opportunities, whether it's manifested through YASNSs or other means.