They seem to think the free market is this thing that can automatically sort itself out through principals of supply and demand where products and services with detrimental impacts are weeded out by consumer choice and incentive to innovate will always drive people to make things better. In this world view, government interference has corrupted the free market, preventing it from delivering the goods. This view, however is not only oversimplified, it's complete BS. First of all, there are many incentives to innovate besides the prophet motive and second, the market is riddled with inefficiencies (more detailed explanation in the video below).But here's a simpler explanation: our minds evolved to live in a small group setting whereas we now live in what behavioral ecologists call a "hivemind". When the size and complexity of a society increases, different rules become more relevant and trying to use the mindset we've evolved to have for a hivemind is like trying to use chess strategies on a go-board. We've evolved to rapidly use available resources to boost our reproductive rates because there was virtually no risk of over-exploitation because predators and disease kept our population in check. Now things have changed and over-exploitation is a real danger but because of human nature this is just an "externality" in the business world; they're motivated by short-term profits because they can't predict what the next quarter will bring so they gobble up what they can (that's game theory for you). Many have compared the free market to how organisms adapt to optimize the resources available to them. But this strategy is why 99.9% of all species are extinct because when conditions changes, they hemmed themselves into a niche and couldn't adapt. We needed government regulation to minimize these inefficiencies in the first place.
Yes the government has its' own inefficiencies and it will introduce some inefficiencies but using those as an argument for "libertarian" capitalism is like arguing that industrialization of agriculture has made it less efficient because the cycling of some minerals is less efficient and the machines have inefficiencies of their own.
In this sense, "libertarian" capitalism can be thought of as a psychological evolutionary atavism; a throwback to the age of hunter gatherers which is maladaptive to modern society.