Because it is an Apple-written browser, Safari is able to use privileged libraries and JIT functionality that it denies to third-party applications. (It is very

Because it is an Apple-written browser, Safari is able to use privileged libraries and JIT functionality that it denies to third-party applications. (It is very difficult to verify the security and compliance of third-party applications that are allowed to perform runtime compilation of code.) This improves performance and battery life. Other browsers would not be able to have the same ability, and so it follows they would sacrifice performance and battery life. As for the security argument, if Safari/WebKit has a problem, it is crucial for all users to apply the security fix anyway, even if a third party browser were installed - using the third-party browser might not be sufficient to avoid exploitation. The last two paragraphs seem to contradict themselves. On the one hand, you are questioning privacy; on the other, you admit that Safari on iOS has exclusive privacy and security features. Nevertheless, forbidding third-party browsers guards against the possibility that such vendors who initially have strong privacy policies might change their minds later.