Probably because much of the current advocacy against porn is driven by feminist works form Dworkin and MacKinnon. It's mostly feminism that is driving it, though religion does factor in.
Because of this, only things aimed at men seem to be attacked, because women are seen as pretty little angels who can do no wrong.
Anyone that's old enough to remember the 1980's and the 1990's probably remember the same group of moralfags that went after Gangster Rap music and video games.
You did had some conservatives and religious leaders that objected to Gangster Rap and violence in video games but most of the moralfagging against these two things came mostly from what I like to call the Boomer Left.
Back in the 1980's and in the early-1990's, you had people like Al Gore that wanted to censor Gangster Rap because he claimed the music promoted crime and was a bad influence on children and how this music should not be seen legally protected speech. What came out of this in the end is the Parental Advisory label which is the current rating system to any music that has explicit lyrics and warns parents about the content found in a single or album.
Al Gore would move on to his next grift for the rest of the 1990's with video games where he claimed violent video games should be seen as an epidemic that should be outlawed. He would team up with Hilary Clinton and they used video games like Night Trap to moralfag their way in Congress about why video games like Night Trap somehow poses a danger to young women. Both Al Gore and Hillary Clinton would fail in their crusade against violent video games and what we got out of this is the ESRB rating system which was a win for the video game industry and a massive loss or moralfags like Al Gore and Hillary Clinton.
Which leads me to porn. Most of the anti-porn rhetoric comes mostly from feminists that want to turn America to be as cucked as the UK where they want laws in place that gives women an amount of absurd power to screw over men. You do have some religious voices that object to porn but most of the anti-porn talking points that you do see comes from feminists that champion stupid shit like no-fault divorce and promote debunked nonsense like the claim men earn more than women for their paycheck.
It's also for the same reasons why Western feminists attack countries like Japan because counties like Japan have not drank the feminist Kool-Aid that would lead to their destruction of their countries as they know them; Japan still refuses to let women keep their family surname when married where they must adopt the man's surname, abortion while legal is still restricted in a lot of ways in Japan, and there's also the fact that Japan is not committing cultural suicide where they refuse to import a bunch of sub-80 IQ migrants into their country which pissed off a lot of Western feminists because Japan doesn't want unchecked immigration (because for some weird reason most Western feminists want to import barbaric third-world cultures from countries that can be classified as objectivity misogynist where said misogynist cultures come from the Middle East and Africa).
If you undo over 50 years worth of feminist legalization in America then watch most of the anti-porn talking points disappear overnight when feminists realize they don't have any power in America anymore. Which is happening right now where some states in America now want to require the mother to provide a DNA test to ensure any kids they give birth to truly belongs to the biological father and some states want to do away with no-fault divorce now.
Porn is a vice, can't argue with this. But the big reason why most feminists object to porn isn't because of the well being of women in the porn industry, it's because women instinctively hate competition and they can't stand men looking at the pretty women found in porn over the ugly landwhales that no one really wants. Women generally do not like competition and they will do what they can to eliminate the competition so they can have the man for themselves.