It's a misnomer to say you can criminalize one part of the transaction and not criminalize the entire transaction. For example in Sweden, where the law was passed in 1999. Those laws didn't actually decriminalize people who sell sex; they introduced new criminal penalties for the people who buy sex. Nothing changed in the legal status for the sex workers themselves. It's impossible for them to operate a legal business. When you criminalize part of a transaction, you're creating collateral damage for all those engaged in it. You are now making them work in a criminalized context.