Every time someone jerks off to disturbing material they strengthen the neural pathway that associates the porn with sexual gratification.
The neurological phenomena you're talking about is called "chunking", and it's a learning procedure in the brain, it's how people learn how to do things like ride a bike, drive a car, ect. It has nothing to do with sexual fetishes, one does not 'learn' a sexual preference.
Porn not only reinforces sexual preferences, but can create them, and after a while is subject to diminishing returns. A lot of people start off with relatively vanilla stuff but then get into really sick shit like loli/shota/furries/gore/etc.
This is the same argument that Ted Bundy used to vindicate himself at his last interview, that reading BDSM porn in his youth planted the seed that led to his rapes and murders. Ted Bundy also surrounded his aunt's bed with kitchen knives pointed at her and waited at her bed to watch her reaction when she woke up with a big fuck-off grin on his face at the tender age of three.
Pedophilia is a lifetime condition that people are born with just as sociopaths are born with ASPD. Pedophiles who had volunteered for castration to get early releases from prison used other means of abusing children upon their release, indicating that their abusive behavior isn't rooted in sexuality at all.
When cops raid a serial killer or rapist's home, they often find massive porn collections over a wide variety of genres that started out softcore, but became increasingly depraved over time.
Most people who jerk off to that stuff won't act on their urges in those ways, but it's still obviously extremely unhealthy for your mind and sexuality.
People who escalate to those extremes were always predisposed to do exactly that. Normal people don't move on to consume extreme "pornography" such as animal crush videos after watching lesbians finger each other. The people you described are sociopaths because they're easily bored and will escalate to achieve a higher rush the same way Eric Harris got bored of shooting people and started searching through lockers instead because murder stopped doing it for him.
It's a matter related to if it is, or it isn't a victimless crime. No animal was hurt or abused in a drawing. Same with other pornographic materials like drawings of underage boys and girls in sexual acts.
It is questionable and disturbing material, but it is fictional and non real.
While that might make sense in principle, I'm of the opinion that pedophilia is unique unto itself and uniquely bottlenecks to a single conclusion. It doesn't matter if they have a harmless outlet to consume, it doesn't matter if they're deprived of any such content, they'll escalate to the real thing with or without it. Consumption of lolicon and shotacon are early indicators of a sexual offender the same way cat killing is an early indicator of a serial killer.
This doesn't include "obscene" porn, which I take to mean like bestiality and CP?
Obscenity laws are designed to be vague and don't describe anything specific because "I know it when I see it", meaning that anything could be determined as obscene if you really wanted it to, and it has, when an indie comic book artist was convicted of the crime for depicting rape in his comic.
the people over at r/nofap and r/noporn are convinced that you can make yourself an autogynephile by watching too much sissy hypno, or bisexual similarly, and if you stop watching porn/jerking off you'll return to being a regular straight dude. I'm not sure how much I believe this is true, but a lot of people report it happening to them.
Because laymen giving self reports anonymously is always medically scientific.
Even vanilla guy/girl porn is actually first person cuck porn.
You have emotional support relationships with every pornstar ever?