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I think you two are not talking about the exact same thing. In my understanding GP isn't at all opposed at kids being kids. Their point sounded more like being about autonomy.

Due to the mobility restrictions of the suburbs (everything can only reached by car) you as a parent are automatically managing more of the time of your kids: Picking them up at school, driving them to organized event 1 or 2 (sports for example) etc.

In the city it's easier for kids to do those things themselves: My kids went to school by themselves after a few weeks in first grade (school is only a few hundred meters away from home, though). This has a bunch of other consequences: They can autonomously meet peers earlier, so they have more free and unstructured time together etc. All in all less parental involvement, and the kids have to (and want to!) organize more by themselves.