It is supposed to work the same way as other legislation does. If you make something illegal then hopefully less people will do it. The same as compulsory seat belts, mobile phones whist driving. Folk say things like "It's impossible to enforce it". And whilst that may be true, it doesn't mean we shouldn't make them illegal.
It's the same with folk who come out with this "Freedom of choice" bollocks. At the time, folk said things like "I have the freedom of choice to get killed in a car crash if I want to" (I might be paraphrasing a wee bit). Society (through our governments) decided that people should no longer have that choice.