Is USAmerica(worlds largest superpower) a successful capitalist country?
Is slavery and Eps stuff a success?
Success would need to be defined then, right?

And your notions on everyone having to be perfect seem to be wrong. The main basis of Communism is who owns the means of production and the level of development. The minority of the ultrawealthy in capitalism vs the majority of the regular people in communism.
Also, general planning vs capitalist planning that focuses on profit and externalises social cost.

And if you want to go deeper into critiques of capitalism and why we need to plan beyond that, I think you lookup aspects like the crisis of overproduction and the tendency of the falling rate of orofit.
Others here maybe better able to explain more on that.