Actually the success of ideologies is more closely linked to the success of its implementations than its merit. For instance, the success of monarchies for such a long period in history was based on their stability. Likewise, it could be argued that the resurgence of democracy was based on instability in the existing regimes, more than any greater merit in the ideology. If the Soviets had been more successful, I can guarantee we'd be saying how the merit of equality of income is why the Soviets were successful, but we'd be wrong, just as saying the merit of democracy is why the US was successful.