While you and the parent are totally correct about the dynamics of power vacuums, I think it's also relevant to note that the robber-baron stuff wasn't exactly

While you and the parent are totally correct about the dynamics of power vacuums, I think it's also relevant to note that the robber-baron stuff wasn't exactly happening in some kind of Hobbesian state of nature - it's right there at the end of your quote: "They did so with the blessing of the US government". This was an environment where centralized authority was weakened to the point that private armies were worthwhile, yet still strong enough to engage in selective enforcement on behalf of corporate powers. Hence, the dynamic where you'd get beaten up by the Pinkertons and then arrested for fighting back. This sort of halfway environment is the worst possible case: in a more total vacuum, opposing corporate power via collective action is more viable; in a society with a stronger grip on a monopoly on violence, corporate abuses are (theoretically) restrained. While untrammeled corporate power and untrammeled government power are both scary, the effective fusion of the two via state capture is the real nightmare. I think that sort of halfway environment, where there's enough state to be worth capturing but not enough to be an effective counterweight, is the default in a lot of the particularly cursed post-colonial nations - Angola and Burma spring to mind - where traditional means of social organization were sublimated into the colonial state, leaving a vacuum when the colonial state itself began to molder.