it surely does not mean anyone is not an agent
It means that taking the agency away would be a good thing (net benefit to the society).
But let's get explicit. Are you saying that -- if it were possible -- forbidding premarital (and extra-marital, presumably) sex would be a good thing? And that if you had a button to push which would make it so, you would push that button?
First of all, the existence of a social norm is different from a law, and we were discussing the former, not the latter. It's true that if you have reason for a social norm, you might have reason for a law. But it may be that the norm would be overall beneficial, and the law overall harmful.
If having a norm or a law against something means that people are not agents, then people are not agents because there is a law against murder. So obviously that does not follow. If you want to call that "taking away agency," you can, but people are still agen...
I've started a podcast called Future Strategist which will focus on decision making and futurism. I have created seven shows so far: interviews of computer scientist Roman Yampolskiy, LW contributor Gleb Tsipursky, and artist/free speech activist Rachel Haywire, and monologues on game theory and Greek Mythology, the Prisoners' Dilemma, the sunk cost fallacy, and the Map and Territory.
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