Of course it won't work, I never said it would
Communists in general are extremely conservative, wanting everything to be tightly controlled and governed by the State.
As pornography doesn't really lend itself to that, they're opposed to it. At the same time they WILL use prostitution as a means to control the population. Of course the system is different, with women being forcibly given to men who please the Party as rewards.
Marx was extremely conservative. His ideas included the murder of everyone who didn't agree with those ideas, and the enslaving of the entire population (effectively prostituting the population to his own greater glory), except for those parts of the population he didn't like (like Jews and other ethnic minorities) which people were to be annihillated (yes, Hitler got his ideas about racial purity from Marx).
Of course religious extremists are against pornography. That's the same for any religion.
Take Islam for example. It bans the portrayal of the human form in art (which porn falls under in this context) completely.
So do several Christian factions (though not catholisism).
That's why they are opposed to it (as well as the depiction of the act of procreation as entertainment which is a waste of the Seed and therefore a sin).
This isn't an American thing, it's a religious thing.
Americans as a people are hardly more prude than others, they're just more vocal about it.