WTF

What stops people now? Like when people sell videos, articles of clothing, and such on sites like Only fans and what not is there policies that somehow punish people for offering more money for someone to meet up?

Most services that are sex work adjacent are extremely paranoid about not becoming associated with prostitution. The website itself can be held liable if they're found to harbor it.

Additionally, the risk of criminal penalties deters people, as well as the risk of social embarrassment from something coming to light. Legalization removes those concerns, and so demand increases.
To continue with the prohibition comparison: prohibition can never succeed, but it does reduce consumption. There's a segment of the population who would be willing to partake in whatever is being prohibited, but isn't interested enough to break the law of work through the criminal connections needed to make it happen.

The import of sex workers isn't really to do with the physical diversity. It's more to do with the willingness of the people, or lack thereof. Tricking someone from a poor country into coming to the US and then extorting them into prostitution is unfortunately often more cost effective than charging people more money.
It's why you see so many billboards and signs around international airports informing potential victims of human trafficking that they have rights and can get help.

It's why countries with more prosperous economies and democracies have higher levels of trafficking into them. People, on average, have more economic opportunities that don't involve prostitution and a greater tendency towards self determination.