Yea, this tracks my observations. A lot of adults make connections in their community through their kids and kids' friends. Kids pick their friends and their parents and guardians just go along for the ride, so when the kids play together, it kind of forces the parents to meet and interact.
Without exception, the parents I meet in the 25-40 age range are what I'd charitably call totally anti-social. Not actively mean (although some are), but just not interested at all in even saying a word to you to pass the time when the children are playing together. They just sit there on their phones trying to get through the experience. In general, these parents project outward an attitude of vague grumpiness and annoyance.
A few of the kid-friends are evidently raised by the 50-70 year old grandparents (never even seen the parents), and these folks tend to be much more social and will shoot the shit with you while the kids play. Much more pleasant and willing to interact while we're forced together. My relationships with them have been civil at worst and friendly at best.
Of course, this is just one person's observations, and yea they are a crude generalization. I'm in my mid-40s so don't have that much in common with either of these groups, but the attitude and behavior difference has been stark!