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?
Why would it be hard to implement? They'd just have to count how many times specific boards are mentioned by specific table rows.
That's fairy simple provided the Yobit developers have any interest or eagerness in this. There are other proposals too like merit introduction etc but it all depends upon the yobit devs.