Every modern and nearly every recent historical society has been a mixed economy. The only reason the middle class exists is because it was fought for, hard, by explicitly anti-Libertarian structures (new deal style reforms and make-work projects, welfare, healthcare, unions, minimum wages, worker protections, tarrifs, GI bill, universities, very high taxes on the rich and very high corporate taxes, publicly owned infrastructure, bailouts) fighting against or protecting free markets from themselves when they inevitably crash and burn and destroy themselves and the societies around them. Without these protections free markets would annihilate the entire middle class in a heartbeat for the sake of "efficiency" as is their nature (the middle class are by definition not the owners of capital so their concerns are not considered by a capitalist economic structure), a process that is occurring albeit more slowly in the US as we speak. Markets are very powerful engines for generating efficiency, so they are good at building economic engines (through exploitation, of course) while ignoring any and all other concerns or consequences. They are a paperclip maximizer. Not entirely useless tools, but horrifyingly murderous and dangerous ones that have a tenancy to seize power with disastrous results wherever they go.