Just a wild guess since I have no idea about the technical aspects in counting-systems: May it be that excluding specific boards are hard to implement to the automated counting performed through the Yobit-website?
It wouldn't be hard to implement. I've been in old Yobit campaign and I remember they didn't paid for posts made in Off-topic and local boards. So, it wouldn't bedifficult to implement, they only need to make some adjustments in their bot.