The USSR had many challenges, especially WWI and WWII happening soon after founding. But pretty much every socialist experiment has ended in dictatorship. We just watched it happen before our eyes in Bolivia. It's worth considering that it may be a problem endemic to socialism.

Private property rights are the bulwark of a free society. You can have all the other individual rights you want, but those are just paper rights unless there are people with private resources to stand up to the government. Once you decide that the government has the right to allocate society's labor and capital as it sees fit, it naturally leads to the government controlling everything.