Because such a small group of title candidates makes the sport boring, predictable and unwatchable.
What Novak did in 2011 is precisely the opposite: we have a new number 1 after 7 years, we have another multiple slam winner after 7 years. So was tennis even more unwatchable before? Or maybe what makes it unwatchable is having Nole
winning slams and breaking the duopoly, not the predictability of the sport?