I've been thinking on this more, trying to divine the root of the impulse, and I think part of it is this:
What makes for good/useful/non-harmful art is going to depend to a degree on the audience. Historical propaganda read by people reading history is going to be very different from the same text being distributed as propaganda.
This is especially true with children. Especially for young children, "showing reality" is often not useful or even actively harmful. Most children's stuff does have some degree of moral instruction, because we don't see young children as sophisticated enough yet to put more complex situations in context.
Obviously, there are edge cases, some children are more mature and some less, but I think most people can agree "not all art is suitable for children".
But your work isn't for children, right? So why are people judging it by the same standards they might a children's book?
One can maybe go off about "kids these days" and how many adults only read YA fiction and expect the whole literary world to be like Harry Potter, but I think that's actually a red herring.
I think instead you increasingly have a generation that had access to adult spaces online from a very early age. Graphic violence, gory true crime, hardcore fetish content - there's a wave of people reaching adulthood who had access to all that stuff online since before they were teenagers.
And I think it has made them go "holy fuck our parents' generation is sick in the head" and that early impression lasted into adulthood. So their instinct is to kinda try and make all art suitable for children, because some part of them always imagines ten year old them reading it.
Combine with this the fact that, because they've always had access to adult spaces online (even if they weren't supposed to be there), the sense of there being a transition from childhood to adulthood has frayed a lot. I think Millennials started it was "adulting" and all, but it does seem that this lack of transition between life stages is making people identify as children later and later, and thus see the need to make more and more spaces child appropriate.
This also leads in to the fact that I, online, seem to see the neo-Victorianism from the "extremely online" crowd. I don't tend to see it in young people who didn't spend their childhoods immersed in online culture, and they also seem more likely to identify as an adult. But I think early, deep immersion in internet culture can be kind of infantilizing.