Imagine that you want to eat a greasy burger. Is this a morally permissible action? Using the consequentialist approach, we would first have to determine all the consequences of you eating a greasy burger. Although this seems a rather benign action, we must admit that, at best, we can only propose some scientific hypotheses about the effect of eating a greasy burger on your health. But, scientific theories and hypotheses are only tentative statements about the world. They are not the same as truth. In other words, we will never know if our theories about the effects of eating a greasy burger are true or not. More importantly, we will never know the full scope of the consequences of any human action.
But, let us, for the sake of argument, assume that we have godly powers, so we can look at any action and know all of its consequences on all people from now to eternity. Suppose, for example, that eating a greasy burger today would shorten your life by one day, and suppose that we know all the consequences of you dying one day earlier (i.e., one more day of pain for your family and friends, one less day of food, water and air consumption, more work for the funeral home in your neighborhood, etc. etc... But, even knowing all that, and much more, won't help us determine if these consequences are overall desirable. Are they good or bad? Depending on who you ask, you might get different answers. All these answers will be equally subjective, so we have no reason to consider one of them to be more valid than any other.
So, even if we assume that we have perfect knowledge, we still can't determine whether eating a burger is morally permissible if we use consequentialist ethics. Note that this does not mean that consequences don't matter. They do matter in individual decisions, but they are also always speculative and subjective in nature, and that's why they are not fit to be moral criteria. Imagine going to jail for eating a greasy burger. This might sound absurd, but if enough people believed that the consequences of you eating a greasy burger are bad enough, they might well put you in jail. If you are not convinced, think again. The prohibition era treatment of alcohol consumption was not far off.
Libertarianism, however, does satisfy this bare minimum required of a moral theory. Libertarianism defines the limits of permissible actions using objectively measureable quantities: space and time. If you own the space in which you want to eat your burger, if you own the burger, and if you don't use anyone else's property during your eating of the burger, then it is morally permissible to eat that burger. Otherwise, it is not morally permissible.
Thus, the reason why libertarianism is superior compared to consequentialist moral theories is not that it makes the world a nicer place, although I believe it does; it is superior because it satisfies the necessary condition for being a moral theory, while consequentialist theories don't. We may argue about whether or not this is sufficient for accepting libertarianism, but we must admit that this reason alone is sufficient for rejecting the status of a moral theory to utilitarianism and its derivatives.