the system depends on you only being able to do one thing effectively, and needing to pay other people to do all the things you need but can't do. When you do that, you have to go through several layers of government and corporate bureaucrats who all squeeze you for a little bit extra just because they've positioned themselves between you and what you need to live. To be self-sufficient is to cut all of these middlemen out from between you and the necessities of life. Gardening is a revolutionary act, it's propaganda of the deed writ small.
The problem isn't living together, it's the people that exploit others based on that fact. People can live together without exploiting each other - that's what a commune is.
No I just want rid of exploitative systems like capitalism and imperialism. Have you never heard of things like the kibtuzim in Israel? Unlike the Soviet Union they have actual working socialism bordering on communism. I don't think they live in forests.
Communes can scale above the level your suggesting to at least hundreds if not thousands of people. If it can't scale above that I still don't see that as a real problem because communes can work with each other, possibly using a different trading system between them.
Edit: There are several socialist/communist economic systems that have been theorised that have communities interacting using a system that is separate from how individuals interact economically like decentralised centralised planning. In a system like that you have the local government/committee control the local economy and then have governments from different areas trade with each other on behalf of their citizens.
There are also systems that don't use communes at all such as socialist market economy. Here workers all have a share in the business they work for and get profit shares.