The idea of this is that private control of companies by independent minded founders should not exist. Only large financial companies like Vanguard and Blackrock should own large stakes in public companies. The practical effect is not to raise more tax revenue, it's to seize control from founders and give it to the financial oligarchy by forcing them to sell.
This is what happens in Russia, Eastern Europe, Saudi Arabia, and other corrupt oligarchies. When a business gets successful enough, the oligarchs of the countries show up and offer a deal that the person running the company can't refuse and force them to sell to the local oligarch gang at a bad price.
If they wanted to raise more tax revenue, they could just raise the top marginal income tax rate up to 98% or raise capital gains tax rates and not totally screw up things by forcing the confiscation of companies from their founders.
This is what happens in Russia, Eastern Europe, Saudi Arabia, and other corrupt oligarchies. When a business gets successful enough, the oligarchs of the countries show up and offer a deal that the person running the company can't refuse and force them to sell to the local oligarch gang at a bad price.
If they wanted to raise more tax revenue, they could just raise the top marginal income tax rate up to 98% or raise capital gains tax rates and not totally screw up things by forcing the confiscation of companies from their founders.