Good question! I believe there are multiple parties at play here.

Pedophilia could be considered a sexual disorder, or even sexual orientation (this doesn’t mean it is a good thing, or that it should be acted upon) in the sense that it’s an innate trait, it’s stable over time, and it contains elements of romantic attraction, rather than merely just being a sexual reaction to a particular stimulus.

There are variants of it too. But, this is a basic model to think about. The clinical criteria goes as far as requiring someone’s attraction to children to overpower their attraction to adults, or for it to have a significant impact on their lives, which they otherwise cannot navigate around. Some have absolutely zero attraction to adults, and sometimes even actual revulsion.

I don’t believe many people who consume this content meet this specific criteria. But, perhaps there are some who do. And there are yet some teenagers who may have fantasies about engaging in activities in peers, who most certainly would not be considered to be pedophilic. Whether they should be engaged in uploading, or consuming fantasies is a whole other debate, altogether involving factors like sex education.

I don’t believe people are convinced into committing terrible acts by consuming fictional content. Rather, people have largely been socialized by society to see pedophilic activities as bad. I am sure you too hold this opinion, no?

Most people would be so socialized, that any depiction of "happy consensual relationships" in a piece of fiction, would be seen as the fantasy that it is. As for depictions which depict rape or clearly non-consensual themes, they wouldn’t of their own existence convince someone that suffering is good, and that they should go about and do it.

Even in the case of pedophiles, they have an attraction to children, therefore they look at content involving children. It isn’t the content that makes them like that, nor the demand. Depriving them of the content meaninglessly may even serve to frustrate them, and further deepen their adversarial relationship with society, which could lead to an increased number of clashes.

https://www.sciencedaily.com/releases/2010/11/101130111326.htm
Some research even suggests that some material (perhaps artificial) might even serve to reduce crime, although this sort of research is highly stigmatized, and very few are willing to engage in it.

So, what does convince someone to commit a crime then? If we apply Maslow’s Hierarchy of Needs, human beings have a certain number of needs, which they need to meet to reach fulfillment. A pedophile obviously has unmet sexual needs. They may also find rationalizations for their behavior.

A fictional media (if it were sufficient for their needs) would waste time they could be spending with actual children, burn the energy they would need to do so, and give them a minuscule, but certain level of fulfillment in their lives. Producing such content might even give their lives some semblance of purpose and meaning, which might otherwise be spent pursuing anti-social goals. This is not an uncommon thing, and a report written in Europe, which I currently cannot locate has theorized as such.

https://www.theatlantic.com/health/archive/2016/01/can-child-dolls-keep-pedophiles-from-offending/423324/
There are also some reports that other aids like child sex dolls can also help to prevent pedophiles from committing crimes. Dr. Cantor’s Non-Offending Pedophiles Paper also makes note of this.

Rationalizations for behavior which lead to crime could come in the form of nambla-like rhetoric, which try to downplay the damage which sexual activity does to children, and may even try to spin it as a "positive thing". However, this is not a piece of fiction which is doing this, but a very specific piece of advocacy from a specific group of people, who may employ the power of persuasion, and cite largely discredited research. Others who are of a more anti-social persuasion may be even more utilitarian, and lack the need for a "belief" to make themselves feel better about their actions.

In this way, I believe there is a very big difference between advocacy from an organization, and whether a specific piece of fiction promotes a specific activity. I truly hope that interactions with nambla-like individuals does not color your thoughts on this matter.

Frankly speaking, nambla-like ideology could even be seen as a sort of religion, for desperate people facing a societal dead-end.

https://www.vice.com/en/article/59nbnq/first-man-sentenced-to-chemical-castration-in-indonesia-said-he-would-rather-die
Of course, there are things which are purported to be solutions, but they involve a great degree of suffering, and due to the coercive nature of society pressing down on them, it may even lead to resentment which could lead to worse conditions like mysopedia.

Regardless of that, it is simply not right to not afford people the proper due process and freedoms here. Just because someone who bears a similarity to them (even in a superficial way for those who aren’t really pedophiles), it doesn’t mean they should have to suffer for the acts of someone else.

Sometimes, individuals who do commit such acts also have other mental disorders, which could have been treated at a far earlier time. But, which aren’t due to flaws in the mental healthcare system.

Many pedophiles, like most people really, probably realize that their actions would have a terrible impact on children, and avoid engaging in sexual activity with them. Unfortunately, some of the loudest people also tend to be the least scrupulous, or the most deluded.

This looks like a classic response to outside pressure. When someone says you’re not doing enough, you over react to make it look like you’re "doing something", and smash any account in your line of fire.

Ironically, the accounts most likely to be in the line of fire are less likely to be the most problematic ones to begin with. This may too be an example of "moderation at scale is hard". Tumblr nuked all the porn on their platform to try to get at a few pieces of child porn.

Even if we agree that action was necessary, for child porn being an absolute evil (which it is, although we can’t shutdown society and free expression for it, it will always exist, and we have to accept that on some level), a simple nudity filter trained on real human beings would have done the exact same job, and many furry / hentai artists would not have been affected.

But, no one ever thinks of the collateral damage from their policies, or even if they entirely make sense.