Regardless, I favor less rules and more freedom for kids for it's own sake. If there are social and/or developmental benefits, that would be icing on the cake.
Where I grew up (near Charlottesville, VA), I had acres of wilderness in my backyard and the surrounding area to explore with my friends. We would build make play forts, climb (real) trees, make bridges over creeks and rivers etc. In the winter we'd go sledding, unsupervised, on real hills that we discovered ourselves .. age ranges from 7 to 10.
Nearby there were a couple old plantation houses (ruins) near the scene of various battles from the revolutionary to the civil war. One even had cannonballs embedded in the walls. To be clear, these were just there, not maintained as museums etc. They were a rumor passed from older kids to younger ones, each mini-generation re-discovering them and the wonders contained.
I bet if our parents knew exactly what we were doing they would have been horrified, that was part of the fun. We did these things without their permission.
When I was about 13, we moved to upper middle class suburban California. Nice, safe, maintained parks. Pretend islands with pretend castles, slides and playground equipment with signs displaying instructions for "proper use." Frankly, boring, synthetic and alarmingly sad.