I agree with your POV. There are horrible things that happen in real life and if your story is about War, or a horrible monster, plague, zombies, then I feel it would be unrealistic and a disservice to not show horrible things happening to everyone, including children.
To be honest, I admit to have been jaded since I suffered a personal loss previously, so the idea that child death, a very grim part of a reality, is taboo from comics or animation, is very odd. Not only that, but I have watched a ton of movies and shows (Stranger Things, IT), even animated shows where children's lives are in danger or they die (Child of the Fireflies, Evangelion, The Promised Neverland, Higurashi No Naku Koro Ni, hell Finding Nemo, The Disney Animated Tarzan).
As long as it's not just for shock value (A Serbian Film is a POS for that) and has a point to the plot, or the setting, etc, I don't see the problem. Could it a personal line for the creator? Of course.
However, there shouldn't be a blanket taboo, especially in stories dealing with some serious topics.