I think perhaps you misunderstand. Most people don't think parents bring their kids along to deliberately disrupt travel. At least, I certainly hope that's not what people think.

But, intent is irrelevant. It doesn't stop it being annoying for some/many people.

As for the picture here. I suspect the reason more people are looking this way than usual. It looks to be a business class cabin. I know many people book business class because it more likely puts you at some distance from the noisier cabins. This looks like they probably have a dedicated business class boarding door. So they likely realise they're coming to sit in the same cabin.

If you book in economy, you're used to and expect it more, I think.