I agree, but add the proviso that since under capitalism capital is power, those with the most capital will slowly find ways to use their capital to deregulate their income streams again.
Supporting friendly politicians, editorial control of the media, or even just the good old Starbucks/Wallmart practice of squashing independent competitors by leveraging economies of scale to outcompete on price - which at the end of the day, the poor customer has to pay attention to. These are all examples of how capital will find ways to get ahead.
Even if companies can't donate, the CEO or every member of the board still can.