But why? I am asking in good faith here, I have never heard proper reasoning for why engaging with loli/fictional children content is somehow worse than any other kink.

I'm not looking to engage in this much further beyond I was groomed with cub porn being a tool to normalize the behavior. Additionally it gave people looking to victimize me a community. And for the record pedophilia was the only one significant enough to mention, but isn't the only moral boundary.