If I recall right, there was a journal of one settler. It talked about how many people slacked off and didn't work very hard on the "commons", and since they were communitarian it was all "commons". Many younger men wondered aloud, the journal said, why they should work their fingers to the bone to support the wives and children of others, when they recieved only "their need" instead of a return proportional to the amount of work they did.
In short, the lack of incentive lead to a lack of hard work. The communitarian fields, worked by everyone, lead to a "I'll do the minimum necessary, and someone else will pick up my slack" attitude, which lead to a short harvest and a very lean winter in which many died. Lack of incentive, you see.
When they changed to a private-property, own-your-production (capitalist) system, people had an incentive to work hard. If they worked their own fields, no one else was going to "take up their slack" and if they worked hard at it they KEPT the results of their productivity.
This is why capitalism produces plenty, and communism/socialism/etc produces "barely enough" and eventually hovers on the edge of starvation.
