First of all I'd say that the 'normal' heterosexual porn necessarily begets the more extreme kinds given that much like with drug addiction there's good evidence that people who consume porn start to not receive the same hit from less extreme types of porn and need to seek out the novelty of more extreme varieties to achieve the same results. Degeneracy is always a slippery slope. Look up the top videos on any of the major porn websites right now and you'll see the truth of this. They're usually some variation of torture, incest or any other extreme deviancy you can think of. This isn't an accident.

The industry itself is also a disgusting hive of addiction and exploitation. Anyone who says differently is in on the racket or currently benefiting from it. Nearly all of the young beautiful porn girls exit the industry broken, addicted messes full of regrets and tales of repeated abuse. Most of them were adults when they got into the game -- some weren't though! -- so I'm not saying they're saintly victims or anything but the industry is like any other vice industry and should be illegal.

Probably the most important part of why porn should be banned is that a society saturated in pornography is one in which children will be exposed to it. In Australia the estimates though they differ from study to study suggest that around 40 to 50 percent of NINE YEAR olds have already accessed pornography. I don't think you have to be some mad puritan or Church lady 'think of the children' type to realize that is a profoundly troubling and negative thing for a society. The second adults accept the presence of pornography in their society is the second they accept it for their children as well.

tl;dr You never have 'normal' porn without the weirder shit, the industry is a cesspool and how about we not have 9 year olds watching this shit.

Is this a serious post? If so youtuber Heck Off Commie just put out a very detailed video on why porn is bad. Basically it's super normal stimuli and fucks your dopamine pathways. It also leads you to chase the dragon. You'll eventually pursue more and more degeneracy. Porn exploits the novelty instinct in men and leads them towards demonic, anti natal, disgusting, unclean sexual proclivities.