Does it matter that we don't know why?

Yes. "I have but one lamp by which my feet are guided, and that is the lamp of experience. I know no way of judging the future but by the past." Presumably we are not discussing the CPC in a charity context solely out of a historical interest, but to guide our future actions.

Paul Krugman writes:

"The leaders of those [frighteningly fast growing] nations did not share our faith in free markets or unlimited civil liberties. They asserted with increasing self confidence that their system was superior: societies that accepted strong, even authoritarian governments and were willing to limit individual liberties in the interest of the common good, take charge of their economics, and sacrifice short-run consumer interests for the sake of long-run growth would eventually outperform the increasingly chaotic societies of the West. And a growing minority of Western intellectuals agreed."

He is speaking of Russia, of course. Krugman then goes on to say that the growth was perfectly explicable by normal industrialization and not by any special governing factors (no 'your legal kung fu is best'):

"Communist growth rates were certainly impressive, but not magical. The rapid growth in output could be fully explained by rapid growth in inputs: expansion of employment, increases in education levels, and, above all, massive investment in physical capital. Once those inputs were taken into account, the growth in output was unsurprising--or, to put it differently, the big surprise about Soviet growth was that when closely examined it posed no mystery."

So. I think no one here would suggest that donating to the CCCP (rather than CPC) would have been very effective, nor did the CCCP government offer much worth imitating.

If the CCCP didn't, the Outside View asks, what makes the CPC different?