I'm in my early 50s and not sure we ever played a pickup game on a baseball diamond. We always played in a backyard. Started with a baseball but changed to a tennis ball when we got older...too many broken windows. When we played with a tennis ball, we threw some wicked curveballs. Everyone in our neighborhood could hit.
My kids have played in a couple pickup games on the local diamond and people were amazed. Someone even made a post about a bunch of kids playing the game on social media because they were so surprised.
In a lot of communities kids playing a pick up game would be chased off the field by city workers getting it prepped for a travel game later that evening.