You can quote up to four sentences to tell us what's happening. Right now, we have no idea why it has an anchor or why it didn't.
I found this on the Hayden Planetarium site: Let there be light: Our profound areas of ignorance notwithstanding, today, as never before, cosmology has an anchor, because the CMB reveals the portal through which we all walked: the surface of last scatter. It's a point where interesting physics happened, and where we learned about the universe before and after it's [sic] light was set free.
The simple discovery of the cosmic microwave background turned cosmology into something more than mythology. But it was the accurate and detailed map of the cosmic microwave background that turned cosmology into an experimental science.
