The article fails to mention that even when the tax code was 90% on the highest earners, most of the successful companies were American, including Exxon Mobil, GM, Ford, DuPont, AT&T...
Anecdotally, I don't think I have ever met anyone starting a business thinking "If I don't make more than 2 million a year for myself, I won't have a successful business." So increasing tax rate beyond a couple of millions a year, or even before, seems a no-brainer to me, at least until everybody gets healthcare and free education.