Ban buybacks and companies would just issue higher dividends instead. Money is fungible, and buybacks and dividends are more or less equivalent mechanisms for companies to return free cash to shareholders.
One of his arguments is that corporations spend a larger % of their net income on buybacks due to exec compensation incentives and many companies do both dividends (which tends to be continuous and a shock to the stock price when removed) and buybacks which are more isolated events.
Using his own data, which by the way, makes no attempt to control for other factors, that change is from 79% to 84% devoted to shareholder returns. That is hardly a 'save the economy' level of change, even if you grant the incredibly dubious connection.