There's a lot of ways (though there are limits) you can derive personal benefit through things that look like corporate expenses but not personal income, and so are not taxed to you or the corporation; these aren't even constrained by corporate taxes.

But, back to the point, absent corporate taxes, you can use corporate retained earnings as a perpetual tax structuring vehicle by choosing to extract and realize income from the corporation when most convenient for you, as well as enjoying any personal benefits tax free that you can slide by as business expenses. It's that permanent deferment piggy bank,not the more limited tax free benefit extraction, that makes it a tax shelter.

And given the high threshold at which estate tax kicks in, this is potentially a multigenerational tax shelter.

Corporate income tax (which is really a retained earnings tax, because expenses are deducted) shuts down the corporation as tax shelter maneuver.