Let me see if I can put it into terms you can understand.
They prosecute people who look at child porn. Not because those people abused the children, but because those people create the demand that causes the producers to abuse children.
You decrease the demand, you decrease the abuse.
Or in another form.
If you really want to stop illegal immigration, you go after the people employing them, not the illegals themselves. We used to do this and it used to be effective.
There are an innumberable number of examples of going after the demand to affect the supply.
