Not necessarily. But this article in Scientific American reminds us of the importance of "free play." I think it might be important for adults too. I think it also indirectly points to the importance of siblings. I can't count how many "only children" I know that have social issues, including myself. I think I've become more of normal (whatever that means) social creature but I'm certain that the lack of constant contact, disputes, and resolutions with siblings resulted in some of my past social ineptitude. I certainly had plenty of time for free play though. In fact, most of my early childhood memories are of free play. Climbing trees, pretending to be superheroes, challenging my cousins to cross the river on logs, and other outdoor adventures come to mind.
According to the article:
“Free play,” as scientists call it, is critical for becoming socially adept, coping with stress and building cognitive skills such as problem solving.It makes intuitive sense. In an organized sport, there is generally an adult in control. Rules exist before we even show up. And everyone already knows what they are there to do, except that one weird kid that was always there (I think that may have been me at least some of the time).
In free play, especially with little supervision, there are no rules except those that are laid out as play progresses by the players. This seems rather important. With no particular authority figure setting the rules up, kids have to learn to organize the rules themselves. They learn through interaction what kind of behavior is appropriate and what isn't. If one kid is too pushy or too bossy, they aren't very likely to be invited to play next time. Hopefully, they learn from this. If one is too timid, they might not have any fun and in theory would learn from this as well.
Creativity is certainly nurtured during free play far more than during organized play as well. You get to be whatever or whoever you want during free play. Development of useful manipulative social skills comes in during free play quite often. If you want to play fairies and I want to play GI Joe (or vice versa) you'll need to convince me to play your game instead of mine. Or, maybe the two of us will agree to play each other's games as an exchange, thereby learning to share. Of course, we're learning to share because it will get us something in return instead of "just to be nice" but as adults, whether we admit it or not, that generally is why people share. That's a discussion for another time.
Here is some more info on free play.