A big exception to this rule for me is when it crosses a few select boundaries, but we're talking the super extreme shit. Loli/pedo shit, for example. Does it make you a bad person? No you can't help it. But it's not okay to indulge.

i have never seen anyone propose this that can muster an argument fundamentally different from (quoting the OP) "it's upsetting to me". what harm does "indulging in it" cause that indulging in noncon doesn't cause? snuff? gore? misogyny kinks? bdsm? feral furry? it seems so awfully selective...

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.