This is definitely not true.
https://en.m.wikipedia.org/wiki/Socioeconomic_mobility_in_th...
It's been 80yr and Japan and Korea are doing fine.
The USSR basically force created a large single market over the course of its existence. If it was such a net win for prosperity the economic would have stuck around.
Same thing with socialized medicine. Nobody says that socialized medicine is impossible, just that it requires a level of taxes nobody wants to pay. Again to use France as an example, health insurance is paid for with a 20% tax split between employers and employees: https://www.npr.org/templates/story/story.php?storyId=924192.... America could easily pay for socialized medicine with such a tax. That’s not how any proponents of socialized medicine in America have proposed to pay for their proposal.
Ironically, that’s just a different form of American exceptionalism. “We can have high minimum wages and socialized medicine like Europe without having higher unemployment and higher middle class taxes like Europe.”