“I was just reading in another thread a hypothetical situation where a little girl agrees to get gang banged by 100 men for a sandwich or something, which I guess is supposed to show how horrible voluntary exchange can be.”
That hypothetical is easily countered: a child cannot give informed consent. This could arguable be different in life-and-death situation: starve to death or accept a high price to live. Easy choice, right? Maybe not. The girl may live to regret the price she paid to live, long haunted by the abuse endured, so informed consent still applies, in my view.
“Where did they come from and why is she in a state of such desperation?"”
They came from the imaginations of people who cannot come up with better arguments.
These extreme hypothetical suggest to me a lack of good argument against libertarianism. “If we adopted your view, and because of that, the moon broke out of orbit from earth and zombies arose and started attacking humanity, would you admit you were wrong?” Libertarian: “WTF?!”
“So by obligation i mean that if I were to assert that the moon is made of cheese during discourse, the burden of proof would be on me to verify that claim, not on you to falsify it.”
Your assertion requires evidence if you want others to take it seriously, but if you say “what if” then evidence is less needed. It is hypothetical.
“if I created a scenario where one man owned all the oil in the world, shouldn’t I have to present the details of how such a situation could arise, especially if this scenario was to illustrate some economic, political, or ethical proposition?”
Yes.