You're conflating the natural concept of a monopoly with the legal concept of a company with total success.
The fed bought the governement with real industrial money, not dollars! The Act enabled it, but realistically, the absence of an Act wouldn't have prevented them from monopolizing...something.
These were titans of industrial era capitalism, ultra rich far beyond what we have today. We need to treat them like peer superpower nations, if we talk about removing them.
Coincidentally...I think that's exactly what's playing out right now.