Yes you absolutely can blame Castro and his hypocritical, corrupt, fanatical insistence on Marxist Leninist economic central planning and state control for the misery and poverty of Cuba. Castro ruled for decades, Cuba is only now slowly leaving his shadow. The U.S embargo was a disaster and a very stupid policy with some blame for Cuba's miseries but the majority of their ruin is very much their dictatorship's doing. I'm sorry, but to avoid this blatant causal relationship, shared by many other countries that never fell under major U.S sanctions but which did apply Marxist central planning, is to avoid the extremely obvious.