Socialists can say for example, if healthcare is left up to the market then monopolies would rise, the quality would become abysmal, the primary goal of hospitals, doctors and insurance companies is now profit as opposed to keeping people healthy. They might claim government is not doing enough. There should be a single payer option or price control options etc etc.
Libertarians and those who like to extol the virtues of free markets and hate government intervention can blame all the brokenness on government bureaucracy and regulation. If only companies could just handle everything themselves it would all be very clear and easy, kind of like with car insurance. There would be competition etc etc.
See, one can defend either position. So it is not 100% clear cut and obvious which is which.