Notice as b tends toward infinity, something unique happens. It provides us with a transcendental zeta function with some fantastic properties. This transcendental zeta function and its properties allow us to study Riemann’s zeta function close to the singularity. This enables us to prove the famous Riemann’s Hypothesis. (See Riemann’s Last theorem article for detail).
See below for the proof of this super zeta function based on Riemann's zeta function.