They refuted the idea that economic activity can be accurately quantified and debunked the gizmos economists use to pretend it can. Every theory is shot down by someone else, and on seemingly solid grounds. There are hundreds of formulas and strategies for determining the direction and range of price movements. Because every attempt to discover an inflation rate is necessarily flawed. We can't just measure inflation the way we measure the height of a tree.
Prices reflect too many variables.
We can't be sure what accounts for changes. It makes no sense to lump together price changes for incomparable goods. Honestly speaking, nothing. There are only specific consumers who purchase specific products and services. Even when the government is goosing the money supply, inflation affects different goods and sectors at different times and to varying degrees.