Capitalism rewards people for getting more done. And so people are incentivized to do so.

Under socialism, that incentive is squelched, or worse.
Further, it becomes popular and easy to be a freeloader.
Just as you cannot see how your actions contribute to the larger whole, you cannot see that your inactions take from it. Socialism may work if some mechanism to show contribution exists.

And yes, the Plymouth colony allowed people to keep what they grew, and so, like overnight, people were growing food in every square inch of the place.