No, because huge apps like league sports and Facebook sell iPhones. They do what they can, but they ultimately can't actually ban MLB or Facebook from the store, or people will sell their iPhone and buy a different phone.
I wanted to answer this by saying others were being unfair and Fortnite doesn't seriously compare to the MLB or Facebook, but man, I'm surprised at how much revenue it actually brings in. Apparently $1.8 billion in the last non-Covid year. That's still quite a bit less than MLB's $19 billion or Facebook's $86 billion, but a lot more than I expected. I still don't think Fortnite is going to have century plus staying power or drive five generations of inherited fan bases, but impressive nonetheless. Actually makes me wonder if Apple would really go that far.
You say that, but they also have set a precedent of doing that before with the Fortnite and plenty of other apps trying to subvert their arguably harsh In-App Purchase rules. I agree though, they try to ban the MLB, NFL, or other video apps with blackout rules based on geolocation, there could be a lot of people doing exactly what you suggest. Now, all of the apps could get rid of their app experience and go to a webapp only experience and circumvent the rules that way.
https://www.epicgames.com/help/en-US/fortnite-c75/battle-roy...