iPhone has never allowed those and it seems to have done alright.

it did add Safari private browsing mode :), but overall iPhone piggybacked off of the Internet, which was created by Military and adult industry were the first large scale content websites that drove innovation

There are nevertheless viewers of such contents on iOS. They pass reviews so long the reviewer testing account only shows SFW sections that nobody uses. The users navigate from such sites to the App Store, and never the other way around, so there's absolutely no need for the app to have anything exposed to App Store.

Yes, absolutely no one uses an iPhone to go to Pornhub and spank themselves into oblivion because Steve and Tim said it's wrong