It really does make you wonder how little some women think of other women when they consider those that didn't have kids for whatever reason, to be empty husks, whilst living their full and meaningful lives at soft play, cleaning up shit and dribble, screaming at their kids not to jump on other kids heads, and never being able to go to the toilet on their own.
Well, that type of thinker (or 'thinker') worries that child-free lives look very, very attractive, and doesn't like being reminded that having children is entirely optional -- that nappies, sleepless nights and maniacal teenagers are not an inevitability. You don't get any Brownie point from the universe for procreating.
Hence the assertion that raising children is the ultimate meaningful activity, and that the two types of people who don't raise children are either (1) tragic would-be-parents who can't have children but who would give twenty years off their lives to be scrubbing baby sick or dealing with your school-refusing teenager, and (2) 'empty husks' whose hedonistic lives of lie-ins, promotions and exotic holidays are underlain with a prickle of unease about the meaninglessness of all this pleasure.
They find infertile people easier to deal with as an idea (it's not a choice), and can sometimes just get their heads around someone not having children because they're out changing the world (sacrificing their own desire for their big work). The ordinary childfree person who says 'God, no -- not for me, not my idea of a meaningful existence' makes them very twitchy, because it calls all their decisions into question.