What would a structure functionalist say about prostitution?

Functionalists believe everything happens for a reason. For example Functionalists believe that crime is a good thing because
Rules are necessary for a society to function.
Rules are achieved thru socialization,
Without the example of those who didn't conform to the rules,
rules would not be able to be made.
Therefore, a society couldn't properly function.
Since prostitution is a crime, functionalist would say a society needs it because it creates rules.

Prostitution therefore justifies the police, courts and laws. As well as promoting morals and education.