That is not widely acknowledged. While the wealth gap may be experiencing recent growth, especially in the postwar period, over the period in which paper currency replaced gold, the wealth gap has improved dramatically.
False cause. There are many significant variables such as technology that have changed over this period. Any claims to cause must provide data which isolates these and the widely acknowledges claims do not.
This is an argument that can be leveled against the vast majority of non-exact science experiments. You can make the same argument against all non-theoretical parts of economics, "large scale" physics, climate theory, and all humanities.
Therefore in most sciences (essentially outside of logic and theoretical mathematics) this argument is considered invalid. It's not wrong, but it's useless and counterproductive : it precludes most scientific progress.
Economics (the practical kind) is the study of a chaotic system that is formed by the intentions and actions of all humans on this planet, and lots of phenomena that don't even originate on this planet (e.g. the distribution of minable materials on our planet is the result of tiny pressure differences in our solar system's previous sun (the one that went nova and eventually re-coalesced into the current one)). Therefore you can obviously say that whatever economics comes up with is inaccurate (limited, and unknown, accuracy), and sometimes has chaotic phenomena (meaning theory and practice diverge a little bit, but the difference blows up quickly over time and prediction versus reality become unrecognizably different).
Even though random large changes are possible, and in fact chaotic phenomena happen regularly outside of economics too (the ejection of rocks from the asteroid belt is one example that is repeated daily), but we happily perform science as if it never does.
That is not widely acknowledged. While the wealth gap may be experiencing recent growth, especially in the postwar period, over the period in which paper currency replaced gold, the wealth gap has improved dramatically.