But Fortnite wasn’t banned because it was or was not a game, it was banned because Apple alleged that Epic violated the App Store rules around payment.
The defense from apple was apparently that roblox and Minecraft to do not in fact constitute games, whereas fortunate does, so the rules are different.
So it's not really entering a credit card number per se; it's more like giving someone else your credit card number so they can give you another number that you type into a different portal to make the digital goods "appear" on the iOS app.
Why are they making children jump through all these hoops just to enjoy an online video game https://en.help.roblox.com/hc/en-us/articles/115005566223