All of the apparent conclusions in the article are counter intuitive, logic and history tend to suggest that you don't stop things happening you simply drive them underground which is when the bad shit really happens?
The American alcohol prohibition is well regarded as leading to the rise in the mafia as there was still demand but limited supply hence money to be made and somebody will always fill the gap.
Hard drugs such as Opium were legal in this country only about 100 years ago and you could buy special "kits" to send to your loved one on the front line, while drugs are now illegal it hasn't stopped people buying / selling / using it just means the quality isn't regulated and you deal with a pusher rather than a chemist etc
The basic premise in the article is that there is actually a problem that needs to be solved and that any and every act of a man paying for sex is a violent act against women, what a load of shit.
If organised crime etc increased in other countries when prostitution was legalised then surely that is a failure of the authorities to stop it, presumably they simply took their foot off the pedal and decided to do not much about anything and turn a blind eye or weren't given the resource to police things properly.
By all means help girls stay safe (and punters for that matter), ensure girls have access to screening and can discuss issues / get help if they want out, crack down on trafficking; forced girls; pimps; under age girls etc but don't assume all punters are effectively women hating rapists.
I'm sure some psychologist could argue that we punters are in fact victims ourselves so perhaps it's the girls that are exploiting us and us that needs the support!