Banning direct wrongs are done because the thing being banned is wrong. The effectiveness of the ban doesn't matter (unless maybe one can show that banning the wrong actually increases the rate at it happens, but that is different from failing to significantly enough decrease the rate).
Indirect wrongs are things that aren't wrong but which we ban in order to stop something that is wrong. If there is no effect banning it, then it isn't justified to have a ban. If I want to ban cheese to reduce murder, is it justified? No, because banning cheese will no effect on the murder rate.
Banning direct wrongs are done because the thing being banned is wrong. The effectiveness of the ban doesn't matter (unless maybe one can show that banning the wrong actually increases the rate at it happens, but that is different from failing to significantly enough decrease the rate).
Indirect wrongs are things that aren't wrong but which we ban in order to stop something that is wrong. If there is no effect banning it, then it isn't justified to have a ban. If I want to ban cheese to reduce murder, is it justified? No, because banning cheese will no effect on the murder rate.