It has nothing to do with that. It has to do with the precision level of the calibration adjustments.
None of this affects the file, just what you see on screen. But since all your decisions are based on what you see on screen, that becomes kind of important.
8 bit video card adjustments quickly result in banding and posterization on screen. But if the adjustments are done in 16 bits internally in the monitor, and then output as an 8 bit signal to the panel, you get 256 evenly distributed steps. No banding.
Plus a whole bunch of other advantages, like much more precise control over white point and black point. That's crucial for achieving a good screen to print match.
In short, put the Spyder away. It has served you well, but now it's time to move on to something much better - true hardware calibration with Spectraview, which works fully integrated with your PA.