Chaffing and winnowing is only possible with a huge bandwitdth.
Try to put in place of a prosecuted internet surfer on a ugly environment:
The amount of bandwidth needed to hide your needle in, and still having a good response time to "share your prosecuted info" is only possible in places with decent telecom services.
As on the steganography case, on those angry environments you are targeted only by the huge amount of bytes regardless they are chaff or not.
You really get unnoticed on an environment where all your neigbourhood do rich web surfing and share lots of family photos, music or any other multimedia stuff that can hide selected chunks of other contents.
I think it is an scenario where quantity is as important as quality.