I know that it is currently in vogue, with the libertarian current in our society and in the tech world in particular, to ask why prostitution should be illegal. People should have control over their own bodies, shouldn't they?
Here is the answer: many of the people selling their sexual services are not in control of their bodies. Beyond the obvious example of people forced into it by violence, there is also a huge population of people that are trying to feed themselves, or their kids, or their addictions with very few options to achieve those ends. That is not liberty.
If it were true that everyone is absolutely free to choose to engage themselves in such a way with no whiff of active or passive coercion by individuals or their circumstances, sure, they should have the choice. But when the choice is 'do this thing or die, or be in pain' that is no real choice.
This industry needs to connect to customers. Sure, something else might pop up, but at least there won't be a central repository for a while. Hopefully that makes it a less viable.