You're assuming that companies will always be able to control the government, but that's not how capitalism works. Competition laws, independent courts and elections can limit corporate power. And if a company becomes too powerful, it can still be broken up or regulated, like Standard Oil in the US. Meanwhile, communism doesn't just have a problem with bad feedback, it concentrates economic power in the state itself. Capitalism spreads power between millions of consumers, workers and businesses. A system that can correct its own problems is clearly better than one that puts most economic power in one central authority.