Your first comment is exhibiting the isolationist mindset of suburnites

Nah, they were just stating the reality. I know you'd like to keep your fantasy about an anarchist utopia intact, but in case you haven't interacted with many people lately, I'll just gently remind you that most people are not that altruistic.

while simultaneously marking mutual aid as anathema to your world view.

They didn't say anything about their personal worldview. Maybe they think that anarchist utopia of yours would be the dream. But they know that it is a dream and nothing more. Acknowledging the prevailing mindset in society and the limitations that mindset places on collectivist social reform is not an expression of personal conviction.

Your first comment is exhibiting the isolationist mindset of suburnites

I don't think you can narrow that general mindset down to suburbanites. People in all kinds of population densities form in-groups and outgroups, it doesn't matter if they are in suburbia, a big city, or out in the country. I lived in Baltimore for a year, and that was probably the most socially isolated I've ever been. The east coast of the US is just a bucket of crabs, everyone trying to climb over everyone else. The people there wouldn't even spit at you for free. My partner grew up in a very rural environment, like "outside city limits, and that city only had one traffic light of the blinking yellow variety" rural. The help they got growing up was from family. They would do odd jobs for neighbors and neighbors would do likewise, but there was always some expectation of barter or compensation for materials and services. They definitely had a concept of private property, and knew their tools, time, and expertise were valuable assets necessary to continue their desired lifestyle.

Please, contrast my experiences with yours. I'd love to hear a first-hand account from someone living in a current anarchist society.