Normalized SoC vs SoC

What's the purpose of the FuelGauge getNormalizedSoC? I know this is what is reported as Particle vitals.

I made a plot comparing soc and normalized values for 4.192V charging voltage. This says 100% normalized soc occurs at 85% regular soc. Is there a reason to do this? I know that my FuelGauge readings tend to drift upward even after charging, sometimes even above 100.

Under certain conditions, the battery will not get to 100% raw SoC. The normalized SoC caps the value so it will appear fully charged in most situations.