An investors net gain is still subject to "confiscatory tax rates" - don't you worry your little head about that. But saddle them with that on top of taxes on costs of doing business - you'll wind up with no risk takers, no entrepreneurs, just a bunch of unchecked commie rats dictating what you may have left of your enterprise to get by with. "Atlas Shrugged"
Maybe some notorious rich and powerful favor "progressive" tax rates (who don't know what money is) - I doubt that it is popular with most. Desire to "escape the tax code" - you bet. Nobody I know is asking for a 38% tax rate with AMT in the wings! That is foisted on the rising middle class by scumbag demagogues pandering to the populous poor wretched ignorant masses who can conceive of nothing better in their miserable lives despite living in this font of freedom and wealth.
Individuals are largely taxed based on their revenue (wages, salary.) Only businesses are generally taxed based on any rational, accounting-based definition of income. The central problem isn't the way businesses are taxed, but the way individuals are taxed--and the fact that rich individuals are treated more like a business, and less like a wage earner.