As Marx wrote of it, socialism was not only to include state ownership of the means of production, but also the abolition of markets, money, and exchange. Every day the Cuban people make countless decisions, transactions, and calculations about which the dictator and his bureaucrats will never know anything. Thanks to the black and gray markets, Cubans most of the time buy and sell and produce, within constraints, according to their own lights. Even if they are obeyed, the planners can't know what the rippling unintended consequences will be. Often they are opposite of what was expected.
Human action is unpredictable that way.
It would take as many bureaucrats as citizens to attempt to pull that off. But even that wouldn't help, because the bureaucrats themselves are already too busy wheeling and dealing. But for such corruption the people would have all starved long ago. The plan is a sham. If Castro has any sense, he knows it.