When argumenting based on statistics, labeling of the graph or text is where the ideology really shines through.
There are those who argue that the increase in the Gini coefficient (i.e. increase in inequality of wealth or income distribution) means that the U.S. is diverging from its historical pattern of more equal wealth/income distribution and that this must be addressed.
Pg's counterargument is that this is actually mean-reversion, and that the comparanda are actually divergent.
This is somewhat important as it goes to the question of whether Gini coefficients tell us what they're relied on for, what a "good number" is, and if we do decide on a good number what the impact of the required policy changes would be.