questions about old party skins accounts

[arizona]

Like just about everyone else who has a rakeback deal, I had to leave party poker for one of their skins to get it. What I can never understand is why doesn't party look at the history of high volume players who are no longer at their site and offer them a direct rakeback deal to come back. For example; john doe has an mgr of 8k per month at party, but he leaves for empire to get rakeback deal of x percent. Why doesn't party say "hey, come play with us again and we will give you x+1 percent". Not only would they gert a high volume player back, but they wouldn't have to pay an affiliate.
Of course, if they offered me this deal I woldn't accept it, but only because I have been very happy with my affiliate and I would not want to take away business from them for 1 or 2 extra percentage points in rakeback. I am just curious about this as it seems like a no brainer.