I don’t think the parent-to-parent factor can be emphasized enough.
Michael Roston

Mose gets into that a lot in the book, that parents want to spend time around people like them (or slightly higher up on the food chain) and use kids to bridge that gap. One of the interesting consequences she details is childcare professionals roped into spending time with each other in an intimate space even though they don’t want to, because their employers unthinkingly reproduce the playdate form based on parent networking.