Article about parenting.
Comment that completely agrees with the premise of the article.
Comment that sarcastically points out that non-parents are still human and can also sympathize with the situation.
Snarky comment that non-parents always make the conversation about themselves.
Comment that you can’t guess what people have been through because there are many reasons why someone might not be a parent.
Comment refering to parents as breeders.
Comment saying non-parents are selfish.
Repeat ad infinitum, ad nauseum.
(Note: “Article about parenting” can also be substituted with “Article about being childless”.)