I think they are talking about faucet type websites.  My assumption is that they would like to be able to filter out those incentive driven sites to make sure their ads are being seen by people who might actually be interested in paying for products/services.

Even as someone who runs a faucet that uses your site to advertise, I see value in this, since I might eventually place ads on sites that aren't faucets and it would be nice to make sure I'm getting meaningful views.

Edit:  I realize that we decide where we want ads to be displayed, but I guess for lazy people it might be nice to not have to visit every site we're thinking about placing an ad on.