Nobles had overthrown most of the monarchs by 750 B.C.
Capitalist economic systems are typically more productive in the amount of resources they develop.
In a socialist economy, the government controls the means of production. This means they would determine how many goods/resources are needed for their citizens. However, in a capitalist society, the amount of goods/resources produced is dependent on the wants of the consumer. This allows businesses to curtail their production to the needs of the citizens rather than the government.
The true vision of Karl Marx about communism is something that objectively would never work in practice. The problem is that the human nature and the Marx's vision of communism are not going very well together. According to Marx, all people should be in the same hierarchical level, thus horizontal hierarchy. Everyone should be paid equally, no matter the type of job, and everyone should get the same services. There's no private ownership and the economy is totally controlled by the government in a manner to be self-sustaining. Big problem in these things is that the humans stride toward progress and success, so by putting everyone in the same basket the creative minds and the successful people are destroyed, while the lazy ones, and the ones that do not have great potential get the benefits without deserving them. The economy can simply not function in a manner to be self-sustaining, and it will always be on the verge of collapse, and there will always be huge problems with lack of food and products.
