Commons - land maintained by the people in common - are a very common thing in non-capitalist societies. People in medieval England used to tend their animals on common land and get pissed at people who let their animals graze too much, eventually kicking them out by force if they continued to act selfishly.

Basically, acting selfishly is treated as a crime. Breaking into someone's home to sleep there when there is a vacant home available is selfish. Taking all the computers from the public library to earn respect in the next village over is selfish. Meanwhile doing good is appreciated and means others will do good to you in turn, but by default people are considered deserving of all basic necessities.

You might get a Mad Max scenario if you magically get unguarded commons by fiat. But we live in capitalism where the commons are looted into non-existence by default. For an anticapitalist movement to be successful, it has to guard and maintain its own commons against capitalism, compared to which Mad Maxoids are child's play. If we live in a society where private property can be abolished, we live in a society where the commons can be guarded.