I agree with this, but on macos they are not entirely tired. On iOS because of the way iOS gets performance (as far as I understand it to be the case) through the iOS shared cache, there really isn't a way to totally decouple safari from iOS.

I guess you could allow an alternate newer safari, but the one that comes with the OS would have to be linked into the blob.

If they can do it on the desktop, Apple can do it on mobile as well.

No, the two are not architected the same. I believe it’s shipped as a dylib on macOS.