Investors can delay capital gains tax by not selling their shares. If they delay them until they die, they don't pay capital gains at all. (Step-up basis for their heirs.)
You kind of want to collect at least some taxes in the year the economic activity happened.
This would be a tax on income not on capital gains. The entities would have to pay out some amount of money to shareholders to cover their tax liability.
You kind of want to collect at least some taxes in the year the economic activity happened.