"It has been stated numerous times that slabbing only adds to the cost"

Why should that be of any concern to you. If someone wants his/her chip graded by a third party and is willing to pay for that service, how has that hurt anyone but him/her?

"You want to sell slabbed chips, you want to buy slabbed chips help yourself, but don't do it in my backyard".

Your backyard may be someone else's backyard as well.