While being vaguely on the side of review being not very useful I would agree with Apple doing that if only to make their position more consistent, even though I am sure every developer would riot if this was the case. (Although I vaguely remember someone saying we provided feature flags to Apple when we submitted builds at Twitter. But do take it with a grain of salt, since I wasn't on the release team and my view of them is vaguely positive in that I think they generally didn't try to use tricks to get through review.)