Hi, Anon! Other people have spoken about this very topic
with more detail, insight and gravitas than I can manage, so pardon me for
summarizing, and interjecting, and hurling you in their general direction.

Most antis, being young and US-based, grew up post 9/11, and
they’re used to the idea of vastly curtailing freedoms as protection from the
boogeyman of the day. They don’t see why the censorship they call for is so
horrific to the rest of us because they’re just used to that kind of thing. And
they haven’t lived through the various fandom purges to grasp that censorship,
once begun, never ends. They could learn from us if they wanted to, we’ve been
expounding fandom history often enough. But they’re also ageist as fuck and don’t
think we should even be here. Once you turn 18, or 25, or something, you’re
officially A Creepy Adult, and definitely should never ever recall what it was
like to be a teen, much less a child. You’re not supposed to have anything to
do with fictional kids, because that makes you a pedo, but if you insist on
being here, you, the aforementioned pedo, are automatically responsible for
raising every real kid who crosses your path.  Uh-huh.

There’s also the influence of the US evangelical and
political far right, with their authoritarian methods, values and control. The
kids in question are growing up under this influence, whether directly in the
house or in the sociopolitical environment. Not too surprising then, that virginity
and sexual ignorance, masquerading as purity and innocence as usual, has such
high social value among them. Add in the SWERF and TERF predation online,
feeding them the queer identity acceptance they aren’t getting at home, but
also indoctrinating them into fucked up ideas of sex and sexuality, and they’re
a right mess. I’ve heard enough stories of those purity ball and purity pledge
kids not being able to turn off the sex repulsion even after marriage and
having utterly miserable sex lives afterwards. Antis are not setting themselves
up for healthy relationships with their rigid rules and misconceptions, for all
that they put the idea of healthy relationships on a pedestal.

@fandom-is-for-pleasure, @fiction-is-not-reality2, @golbatgender, @xenoqueer and @freedom-of-fanfic have far more coherent thoughts on the matter, with plenty of research and experience behind them.

I take it on a case by case basis to see if the antis genuinely
do have such a poor grasp of the fact/fiction divide that they see no
difference between themselves and a cartoon, or if it’s all just performative
screeching from a convenient angle for the cyberbullying. Probably a mix of the
two for the population as a whole. Some of them are true believers, others are
hooked on the pseudoactivism high, and some are definitely doing it because
they lack the spine to break away from the peer group and risk the resulting
censure.

I know the fact they’ve been raised to see danger everywhere
plays a part, and the messed up ideas about sex don’t help, but I can’t help
but think it’s bloody egotistical of them  to think that every adult in their vicinity is
a filthy predator who is just dying to get into their shorts. I mean, kids,
have you looked at yourselves? You’re only what you’re expected to be at your
age, half-formed, undergrown and painfully ordinary. You have no interests, no knowledge,
no manners, no experiences, no insight, no grace, no poise, no resources, no
skills, not at any level an average adult would be interested in. People don’t
thirst after somebody who has nothing to bring to the table. We WANT you to
stick to your age group until you actually grow into something.  Fictional underaged characters, unlike real
teens, are made to be attractive. Smooth and suave or at least entertaining in a way
you guys just aren’t, and won’t be for some time yet, in ways many of us aren’t
either. They’re meant to stir up interest that surpasses demographic barriers
to maximize viewership and profit. Shipping them is a natural outcome of them
being so damn hot and cool all at once, and has nothing to do with the likes of
you. Get over yourselves.