If meleers and rangers were able to snare in this way, then two more things would be needed: Mages would need better armour. That is the sacrifice they make to be able to bind/snare/entangle. If a meleer could snare them they lose the advantage they have over a meleer. For the warrior ability, mages would have to have some resistance to it. Likewise meleers would need some resistance to the ranger ability. Just keeping the triangle in order (as rangers have considerable resistance the mage ability).