Pre-1995 the average age kids were allowed outside to play independently (without adults present) was 8-years-old. Post-1995 the average age was 12+. Historically, ages 8-12 was the period kids learned to practice independence. Now it’s much later and kids are not being readied for the outside world, hence the proliferation of “tigger warnings” and the insistence on protection from “hate” speech in college, etc.
See Haidt’s excellent book, The Coddling of the American Mind: How Good Intentions and Bad Ideas Are Setting Up a Generation for Failure.
The website he references is letgrow.org.