The problem with that logic is you're treating economic systems as if they all exist in a vacuum, and you're setting up a circular argument of if its successful its actually because capitalism, if it fails it must have been socialism.

It completely ignores the decades of external hostility toward any nation that attempted to build a socialist economy. Almost every attempt has been met with near immediate intervention from captialist super powers, particularly the USA. Nixon activeley worked to cause the military coup in Chile, Cuba has faced the longest trade embargo in modern history (and yet still managed to outperform its peers in the region in healthcare and literacy). Its unscientific to attribute these struggles purely to internal failure when they are subject to deliberate economic warfare.

Secondly, your definitions are being stretched to fit your thesis. Scandinavia is not "socialist flavored" it IS a social democracy, with free markets. Claiming China's success is from captialism is ignoring that its economy relies entirely on state owned land, state owned and controlled banks, and state owned companies, and mandatory five year plans coming from the state.

If we classify any successful state-led initiative as "capitalist" and any blockaded, intervened upon state as "purely socialist" then the argument is an unfalsifiable truism.