> why PornHub and OnlyFans are immune

They're not. I highly recommend the podcast "Hot Money: who rules porn". It's about the internet "revolution" of porn, when it went from DVD to the Internet. It's very interesting and sometimes hilarious.

4 fingers are OK. 5 fingers are NOT. The payment card cartel has an unofficial list of what is and isn't OK to show. It becomes a different act when all fingers are involved and they don't want that. I kid you not.

https://www.pushkin.fm/podcasts/hot-money/hot-money-who-rule...