This feels like it's "DoubleClick For Publishers or Bust."
Admittedly, I've only been on the DevOps side of content marketing -- and even at that, only on the cloud infrastructure side of it -- but, I think that just about everyone knew that while writing your own content and then selling your own ad inventory was ideal, if you couldn't sell your own ad inventory, DFP was the second best play for the income.
To me, this screams, "Even if you have other ads, if they're not DFP-compliant, we won't show them if they are from our browser."
I may be completely wrong...but, who knows.