Who are Rob and Kristin?

Jason Zengerle mentions in a post that due to his wife's subscription to US Weekly, he now knows who Josh Duhamel is. I, however, do not know of this person. As I don't know more than half the people mentioned in celebrity magazines. It reminds me of when Marge Simpson's elderly mother says about Judge Reinhold, creakily: "I don't know who that is."

Is this a new phenomenon? It seems that, back when I was younger, people in their thirties (who were not Amish or living under rocks) could identify most celebrities mentioned in People magazine. Is there a greater divide between mass culture for older and younger people than there ever was?

By the way, speaking of celebrities over time, can I just say how surprised I am that the following celebrity couples are still together: Ric Ocasek and Paulina Porizkova, Demi Moore and Ashton Kutcher, Woody Allen and Soon-yi Previn.