Because the labor of cooking for 100 people isn't 100x the labor needed to cook for one. In grad school I lived in cooperative housing where one day every other week I had to help cook the evening meal for everyone else and just got to eat the other days. It was far more efficient than cooking every day for myself and far cheaper than restaurants.
And what if you like to eat healthy but the other people like to eat lots of meat and processed food? Communes are great if nobody has mutually exclusive preferences
We had a vegetarian and a meat entree choice at each meal and the meals were fairly balanced. If there was anything to complain about it was that the food tended to be not highly spiced in order to reach the common denominator. But we had hot sauces and the like so that people could spice things up if they wanted.
Oddly enough, when I lived in more rural/suburban settings, I never really encountered anything I'd consider communal or primal/"paleolithic" but when I moved to a bigger city, I found many more ways to address those desires.
Even if it's just having a corner bar where neighbors stop in for a meal or a beer in the evenings or getting together with nearby friends on various nights for board games or cookouts, I see a lot more community and shared activities. Much of it is only enabled by the proximity of urban life where the need to drive over to meet up is minimal or nonexistent. When I lived in the "boonies", any gathering had to be a lot more scheduled since you had to account for driving.
Speak for yourself. All I see is forced interaction with people that are around you for reasons that have nothing to do with your choice to spend time with them.
Except in the paleolithic these people would be your extended family, the friends you grew up with, etc. And because of the cultural homogeneity of such societies, you would get along better with them than people get along with their families today.
In the modern context, these would be people you selected.
