When man became a farmer he produced a surplus of food at harvest that he had to store. What is stored can be taken by others. People found that they could raid those with a surplus and take their food. Hunting parties could just as easy become a raiding party. So cities with walls developed.
It requires a critical mass to have
enough resources to defend any type of stored resource. The only alternative is to hide said resource.
History shows countless examples of stored resources being taken by force.
It would seem that a functional community is critical to defending a stored resource not to mention producing said resource.
There also seems to be and advantage in forest gardening due to the fact that food can be produced at different times of year and some can be available year round.
If an annual crop dies or is destroyed it can be a major setback.
Trees and shrubs may not fruit well in a given year but may do well in following years.
Using diverified crops also makes it less likely that all food plants will be discovered and taken where a
root cellar is likely to be cleared out.
Another factor is that resources can be increased over time. Think of a tree growing, a herd increasing, farm assets being added, soil being improved, etc.
I see the advantage of functional community but I would add in the advantage of multiple food sources a food forest can offer instead of just annual crops.