Apple will not allow other browser engines because they are a subset of "programs that run arbitrary code".
Allowing anyone to put their browser engine on iOS through the App Store would open the door to a wide variety of security problems. It would also effectively bypass the App Store, as Google (just as a totally random example) could release their own iOS "browser" that's actually their own platform for apps that they sell. Not to mention inserting their own ads into anything people browsed on it. And tracking literally every single tap and text entry that people do in that browser, including bank passwords, credit card info, etc.
On a platform like the Mac, that doesn't matter very much, because it's small enough that basically no one would bother.
On iOS? If you could get 0.0001ยข per website visit from even 1% of iOS users, that would be a money-printing machine.
Allowing anyone to put their browser engine on iOS through the App Store would open the door to a wide variety of security problems. It would also effectively bypass the App Store, as Google (just as a totally random example) could release their own iOS "browser" that's actually their own platform for apps that they sell. Not to mention inserting their own ads into anything people browsed on it. And tracking literally every single tap and text entry that people do in that browser, including bank passwords, credit card info, etc.
On a platform like the Mac, that doesn't matter very much, because it's small enough that basically no one would bother.
On iOS? If you could get 0.0001ยข per website visit from even 1% of iOS users, that would be a money-printing machine.