The stock market represents a tiny and shrinking sliver of the overall economy. https://businessreview.studentorg.berkeley.edu/why-your-favo.... In many cases there is no distributed class of shareholders, just a concentrated set of owners, so both this and the argument it was responding to about wiping out shareholders are irrelevant.

For companies that are publicly traded, if you were to wipe out the shareholders, that would disproportionately hurt financial institutions that pick and choose stocks and concentrate their holdings and exert influence on the corporate policy over passive investments from the average Joe's retirement fund. To the extent that it's "just a tax", it's a tax that's progressively higher on the people more likely to be at fault.