I just thought of another reason why communism sucks.
We often think of evolution as pertaining solely to biology. However, it applies to any system that both replicates and is capable of change.
Ideas evolve just in the way that animals do. If a new idea is well suited for replication, than it will do so. If a new idea is not, than it won't. An idea is well suited for replication if it is profitable (not necessarily in the money sense) for its host. For example, if I have an idea, say, how to make a product more efficiently, than this idea is very profitable for me. Others will witness it, note its profitability, and replicate my idea. Such an idea is very fit for the environment.
If conversely, an idea is not profitable and harms its host, it is not likely it will reproduce, and it will die.
Now, lets consider the two different environments of capitalism and communism. In capitalism, what is profitable for a host is well defined. Ideas (not all, but many) reproduce because of their financial merit. Capitalism is a very hostile and demanding environment. As, a result evolution of ideas is much faster. Just as a competitive environment jump starts biological evolution in the wild.
In communism, host profitability is far less defined. Because of the lack of monetary reward for good ideas, it is a much different environment for ideas. It is an environment in which weaker ideas can thrive because they offer virtually as much profitability to the hosts as a strong idea would: little to none. In such an environment, idea evolution stagnates, just as non-competitive habitats cause biological evolution to stagnate (look at the animals that have little competition in the wild, some haven't changed much in millions of years).
If you think about it, the only reason ideas evolve progressively at all in communist societies is because the world economy is capitalist. A communist society here is not a pure communist society, it is a communist society nested within a capitalist society. An entire communist nation in the world economy is akin to an individual in a capitalist economy, it must have somewhat competitive ideas or it will not profit. Unfortunately this is not as powerful because countries don't have ideas, people within them do.
In other words, the only reason ideas evolve progressively in communist societies is because they must compete with capitalist societies in which ideas inherently evolve progressively. If one could imagine an entire world that was communist, free of competition, the progressive evolution of ideas would cease, and the evolution would be slow and directionless.
Thus, an isolated capitalist society, because of its competitive environment for ideas, will progress faster than an isolated communist society.
I'm just sayin' is all.