[throway98752343]

Prostitution has effects beyond the two parties exchanging money for sex by making a market for something we don't explicitly buy and sell, similar to human organs reclining on airline seats. https://www.nytimes.com/2014/08/28/upshot/dont-want-me-to-re...

It's easier to understand by flipping the situation:

Let's say society's age-old tradition was that men MUST pay women for sex, and it's shameful (even illegal) not to. But a few women say no, we want to be able to have sex for free. If the men know that free sex is now a real option, why would they keep paying for it? This freedom would drive the price of sex down, and could cause the sex market to collapse.

The equivalent in our timeline is if sex went from being generally free to always having a price.