I think some people are beyond reasoning with.
I tend to avoid those threads now because I know it's just going to be used as a place for them to concoct some wild and ridiculous fantasies that the child-free are spending their abundance of free time choking on our bitterness at not having kids and writhing around in our hatred of all children. I imagine some have even painted us with the pointy noses with the boil on the end, and the pointed hat for good measure.
The reality is that most child-free people couldn't give a toss about them or their children and don't spare them a second thought.
The other reality is that no one hates children more than people who have had children. I'd bet if many of these posters were honest-they only love/care about their own children and loathe other kids. How many threads have been started by parents complaining about other people's kids? Loads.
I often think a lot of the nasty comments from parents to CF people come from people who are deeply unhappy with their choices. I wonder if they see in us a life they could have had if they'd made a different choice but instead of acknowledging that, they'd rather shit on us to try and prove to themselves that their choice was the best choice, really.
I just don't see a lot of genuinely happy parents who are fulfilled in their choices making these kinds of nasty comments to people who have made a different choice to them.
There's also the fact that some people really can't wrap their head around people living a different life to them and making different choices. They have a very rigid view of what a "successful and happy" life is and when someone else deviates from that path, they take it as an affront to them and their beliefs and ultimately their choices.