I have heard it said that capitalism is not a system, it is the anti-system. This is the true beauty of capitalism — it is the only way for human beings to interact with each other without compulsion. Every other approach to organizing society involves some group of people using physical force to coerce other people.
(Go read the whole thing.)
I couldn't begin to count the number of times in online discussions I have been challenged to come up with a "better system" when I have made ethical objections to government interference in the economy. But that challenge presupposes a system, wherein "some group of people [use] physical force to coerce other people." By accepting this premise, that the free market is a system to rule others by force, you unnecessarily cede the most important quality of your argument.
Once you give that up, the accusations start flying that you want oppressive monopolies and tainted food. And, if you want this, then you're not for freedom, but are secretly for a form of fascism, controlled by corporate fat cats.
Warren's observation that capitalism (free market) is the "anti-system" is right on point. If you're not imposing a system on others, then you (and those who don't fight against freedom), don't have the control necessary to maintain monopolies or to stop people from boycotting stores that sell tainted food. People like choices. They don't like risking their health buying food from a someone with a bad reputation. Why would giving them the freedom to make their own choices result in large numbers of bad choices?
Also embedded in the "better system" challenge is the ambiguity of "better." Better for whom? In a command economy, one can always find those who are better off (at the expense of others). But each individual gets to decide what is better for himself or herself, and in a free society, that individual gets to make choices for the better.