It was only a matter of time before they all start to try this (I emphasize try, it probably won't last)
If I want to buy traffic, why would I buy unproven TGP traffic? Aside from the Hun and maybe one or two more, they don't convert well enough to justify the cost!
Warphead and Rip both had valid points. If they want us to buy positioning (which in itself is starting to become a more popular offering for traffic generating programs) than they are going to have show me and I'm sure other webmasters that they not only get the hits but that they convert a hell of a lot better than most TGPs. They must supply quality traffic. TGP's are not necesarily know for quality traffic generators on a whole.
There are excepions to this of course. The Hun, being one right off the top of my head.