You know the kind of thing. Someone posts about a mother of 5 children allowing the kids to behave outrageously in a restaurant and people come back with:
"YABU. How do you know that all five children don't have SNs."
"YABU. How do you know she was their mother? She could have been a family friend whose christian name just happens to be 'mum'".
Imagine if people went on like that in RL. You would never, ever be able to have a proper conversation because it would just drift off into fantasy land after 5 mins.