By your definition of "communism", it has never existed and never will exist, since any country that tries it will get stuck at what you are calling "state capitalism".
While I agree that "state capitalism" is a fair description of the current system in the US and other Western countries, I don't think it's a fair description of the Soviet Union, or of Pol Pot's Cambodia, or of the People's Republic of China under Mao (to give some examples of states that are usually called "communist"). It might be a fair description of the PRC today (even though the PRC still calls itself "communist").
I would agree, though, that all of those regimes are examples of central planning.
> By your definition of "communism", it has never existed
Yeah in communist theory, “communism" as a thing is an ultimate goal (and in many schools of communist thought, a relatively distant one).
> and never will exist, since any country that tries it will get stuck at what you are calling "state capitalism".
No, only the Leninist-derived approaches that try to bypass private capitalism get stuck in state capitalism (or migrate from that toward a system that looks a lot like fascist corporatism, as in the PRC.)
The displacement of the system Marx originally described as “capitalism” with what has been described as “mixed economies” is closer to what you might expect if Marxist (not Leninist) Communists tried to implement their program of moving toward communism in the conditions Marx saw as necessary to begin that transition.
> While I agree that "state capitalism" is a fair description of the current system in the US and other Western countries
It is not, it is a description Lenin made of a deliberate choice made by the USSR as a transitional step, which doesn't resemble anything done in the US very closely.
> I don't think it's a fair description of the Soviet Union, or of Pol Pot's Cambodia, or of the People's Republic of China under Mao (to give some examples of states that are usually called "communist").
All of those involved the state acting in the role of a major or sole legally tolerated capitalist. It's possible to imagine, I suppose, central planning in a decentralized, cooperative, voluntary way without that feature, but no actual regime has done that (though subsidies and incentives that fall short of coercive directive commands in mixed economies are, at least, something vaguely in that direction compared both to the absence of central planning in pure [private] capitalism and the authoritarian central planning in “communist” state capitalism.)
While I agree that "state capitalism" is a fair description of the current system in the US and other Western countries, I don't think it's a fair description of the Soviet Union, or of Pol Pot's Cambodia, or of the People's Republic of China under Mao (to give some examples of states that are usually called "communist"). It might be a fair description of the PRC today (even though the PRC still calls itself "communist").
I would agree, though, that all of those regimes are examples of central planning.