Isn't it weird to imagine someone having the gall to say that in person? It's not even clear what they're hoping you'd do even if you did somehow agree.
When parents watch their kids, it's not "babysitting" it's being a parent. You know, the thing they CHOSE to do. If it's a nightmare for them, then maybe they made the wrong choice.
They said it CAN be a nightmare when it's bad weather. Being a parent is hard, and there are parts that are mentally, physical, and emotionally exhausting. Especially when they're so young they could die just sleeping the wrong way.
You're being unnecessarily obtuse and combative. It brings nothing to the table and alienates the people you're talking to. If you want to be taken seriously, try approaching the subject with a little bit of maturity and empathy. You can even have the same message that someone isn't right to have kids, without coming across like a random asshole on the Internet