Just the Chinese and Indian cases seem more than enough data to make this case. Both economies stagnate behind the world trend until they open up free markets, at which point their economies explode and a billion people are lifted out of abject poverty nearly overnight. There is an arguable case for strong welfare states, but true socialism has literal mountains of evidence against it.
China and India are heavily state-managed and in no sense are they genuine laissez-faire free markets. China still thinks of itself as Communist.
True socialism - on the soft European model - has literally mountains of evidence for it.
The basic problem is maximising productive - i.e. innovative and practical - activity, and not allowing the economy to financialise, which replaces actual activity with meaningless proxy casino activity.
Capitalism on its own concentrates wealth and chokes off its own air supply. Government management on its own ossifies into bureaucracy and oligarchy.
There's a sweet spot between the two where government provides stable markets, seeds R&D, and prevents excessive concentration of wealth and power, but talented and inventive individuals are still rewarded for talent and invention, and the cost of entry for new business ideas is as low as possible.
