ADA4177: What is the advantage of using integrated over-voltage protection instead of building it external to an op amp’s inputs?

An external circuit often includes a series resistor and clamping diodes on the inputs. Leakage current through the diodes will cause a voltage drop across the series resistor, creating an offset error on each input. This error degrades the common-mode rejection of a precision op amp, adding error to the signal. The ADA4177 provides OVP and eliminates that error.