If I read the above posts correctly, it sounds like it's not just Google that benefits; supposedly Google provides ads and such, which provides the publisher with revenue -- the publisher would otherwise have to find ad networks and such themselves. If a publisher already has advertising revenue sorted out, and they're OK with the expense in terms of time spent managing that, then there's little incentive and so they pass.

How much of that is correct? I don't know. I'm just explaining what (I think) the posts above were trying to say.

(Edit: spelling)