That doesn't happen. The kind of pressure I mentioned is more applicable for the childfree couples than the incels or spinsters. Said incels and spinsters are probably extrapolating the "why don't you have a boyfriend/girlfriend?" question their relatives ask at holiday dinners out to it's logical conclusion.Parents wanting grand kids is pretty common. What I don't believe is when the redditors on r/childfree complain about random strangers approaching them and asking why they don't have kids yet.
I can understand people not liking the idea of having kids; they're very often foul smelling simplistic mess making machines with very poor table manners and no volume control. The rewards for having children are often intangible or very personal, but they are there.
Disparaging people for choosing to have children is strange, it's like that thing homosexuals do when they call others "breeders" for having kids.
I suspect it's a sour grapes kinda thing for the childfree singletons.
Not so sure on the couples, that just seems like a fear of responsibility when it's not some medical or economic stymie.