I'm not blaming libertarianism at all.
I'm saying that implementing freedom of contract - libertarianism - would guarantee that things get worse, and asking how you can reconcile that with the fact that you dislike monopolies, using historical examples to demonstrate my point. As I said, oil barons did not pass legislation giving them a monopoly. They simply defined the terms by which they would do business with other parties, with the end result being the creation of a monopoly.
How would modern libertarianism avoid this outcome, assuming you do in fact believe in freedom to contract by whatever terms you consensually agree to? And if it cannot avoid this outcome, it is clear that you care little for outcomes and care only for the means by which we conduct ourselves. That is all. I'm asking you to explain this contradiction.