They are, but that doesn't mean all iOS browsers are equal. Some of them have built-in content blockers, or security features, or Tor, or even just a nicer UI.
Also, due to EU legislation, Apple will soon have to allow alternative engines on the App Store, so Mozilla and Google are working on versions of their iOS browsers with Gecko and Blink, respectively.
I’m curious to see how Apple will handle that. I’m thinking that they’ll have a Europe-only version of the App Store for compliance, but it will be against Apple’s TOS to access that version of the App Store from other regions.
I’m also wondering if they’ll make two versions of the iPhone, one which complies with EU standards for charging cables, and one for the rest of the world where they can continue to get away with their proprietary standards.
Apologies if Apple has already announced their plans but I’m unaware. Press release or not, though, I’ll still be skeptical until I see what actually happens.